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  • 1.
    Abrashev, Miroslav V.
    et al.
    Univ Sofia St Kliment Ohridski, Fac Phys, Sofia 1164, Bulgaria.
    Chernev, Petko
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik. Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany.
    Kubella, Paul
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany.
    Mohammadi, Mohammad Reza
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany;Univ Sistan & Baluchestan, Dept Phys, Zahedan 9816745845, Iran.
    Pasquini, Chiara
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany.
    Dau, Holger
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany.
    Zaharieva, Ivelina
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany.
    Origin of the heat-induced improvement of catalytic activity and stability of MnOx electrocatalysts for water oxidation2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 28, s. 17022-17036Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Catalysis of the oxygen evolution reaction (OER) by earth-abundant materials in the near-neutral pH regime is of great interest as it is the key reaction for non-fossil fuel production. To address the pertinent stability problems and insufficiently understood structure-activity relations, we investigate the influence of moderate annealing (100-300 degrees C for 20 min) for two types of electrodeposited Mn oxide films with contrasting properties. Upon annealing, the originally inactive and structurally well-ordered Oxide 1 of birnessite type became as OER active as the non-heated Oxide 2, which has a highly disordered atomic structure. Oxide 2 also improved its activity upon heating, but more important is the stability improvement: the operation time increased by about two orders of magnitude (in 0.1 M KPi at pH 7). Aiming at atomistic understanding, electrochemical methods including quantitative analysis of impedance spectra, X-ray spectroscopy (XANES and EXAFS), and adapted optical spectroscopies (infrared, UV-vis and Raman) identified structure-reactivity relations. Oxide structures featuring both di-mu-oxo bridged Mn ions and (close to) linear mono-mu-oxo Mn3+-O-Mn4+ connectivity seem to be a prerequisite for OER activity. The latter motif likely stabilizes Mn3+ ions at higher potentials and promotes electron/hole hopping, a feature related to electrical conductivity and reflected in the strongly accelerated rates of Mn oxidation and O-2 formation. Poor charge mobility, which may result from a low level of Mn3+ ions at high potentials, likely promotes inactivation after prolonged operation. Oxide structures related to the perovskite-like zeta-Mn2O3 were formed after the heating of Oxide 2 and could favour stabilization of Mn ions in oxidation states lower than +4. This rare phase was previously found only at high pressure (20 GPa) and temperature (1200 degrees C) and this is the first report where it was stable under ambient conditions.

  • 2.
    Araujo, Rafael B.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Banerjee, Amitava
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Panigrahi, Puspamitra
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Hindustan Univ, Ctr Clean Energy & Nanoconvergence, Chennai, Tamil Nadu, India.
    Yang, Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Sjödin, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Araujo, C. Moyses
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden.
    Designing strategies to tune reduction potential of organic molecules for sustainable high capacity batteries application2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 9, s. 4430-4454Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organic compounds evolve as a promising alternative to the currently used inorganic materials in rechargeable batteries due to their low-cost, environmentally friendliness and flexibility. One of the strategies to reach acceptable energy densities and to deal with the high solubility of known organic compounds is to combine small redox active molecules, acting as capacity carrying centres, with conducting polymers. Following this strategy, it is important to achieve redox matching between the chosen molecule and the polymer backbone. Here, a synergetic approach combining theory and experiment has been employed to investigate this strategy. The framework of density functional theory connected with the reaction field method has been applied to predict the formal potential of 137 molecules and identify promising candidates for the referent application. The effects of including different ring types, e.g. fused rings or bonded rings, heteroatoms, [small pi] bonds, as well as carboxyl groups on the formal potential, has been rationalized. Finally, we have identified a number of molecules with acceptable theoretical capacities that show redox matching with thiophene-based conducting polymers which, hence, are suggested as pendent groups for the development of conducting redox polymer based electrode materials.

  • 3.
    Araujo, Rafael B.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Islam, Muhammed Shafiqul
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Natl Univ Bangladesh, DSHE, Dhaka 1000, Bangladesh..
    Chakraborty, Sudip
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Ahuja, R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Predicting electrochemical properties and ionic diffusion in Na2+2xMn2-x(SO4)(3): crafting a promising high voltage cathode material2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 2, s. 451-457Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sodium ion batteries have emerged as a good alternative to lithium based systems due to their low cost of production. In this scenario, the search for higher voltage, sodium cathodes results in a new promising alluaudite structure Na2+2xMn2-x(SO4)(3). The structural, electronic and Na diffusion properties along with defects have been reported in this investigation within the framework of density functional theory. A band gap of 3.61 eV has been computed and the average deintercalation potential is determined to be 4.11 V vs. Na/Na+. A low concentration of anti-site defects is predicted due to their high formation energy. The biggest issue for the ionic diffusion in the Na2+2xMn2-x(SO4)(3) crystal structure is revealed to be the effect of Mn vacancies increasing the activation energy of Na+ ions that hop along the [001] equilibrium positions. This effect leads to activation energies of almost the same high values for the ionic hop through the [010] direction characterizing a 2D like ionic diffusion mechanism in this system.

  • 4.
    Arvizu, Miguel A
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Qu, Hui-Ying
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Harbin Inst Technol, Sch Chem & Chem Engn, MIIT Key Lab Crit Mat Technol New Energy Convers, Harbin 150001, Heilongjiang, Peoples R China.
    Cindemir, Umut
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Qiu, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Rojas González, Edgar Alonso
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Granqvist, Claes Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Electrochromic WO3 thin films attain unprecedented durability by potentiostatic pretreatment2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 6, s. 2908-2918Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrochromic windows and glass facades are able to impart energy efficiency jointly with indoor comfort and convenience. Long-term durability is essential for practical implementation of this technology and has recently attracted broad interest. Here we show that a simple potentiostatic pretreatment of sputterdeposited thin films of amorphous WO3-the most widely studied electrochromic material-can yield unprecedented durability for charge exchange and optical modulation under harsh electrochemical cycling in a Li-ion-conducting electrolyte and effectively evades harmful trapping of Li. The pretreatment consisted of applying a voltage of 6.0 V vs. Li/Li+ for several hours to a film backed by a transparent conducting In2O3: Sn layer. Associated compositional and structural modifications were probed by several techniques, and improved durability was associated with elemental intermixing at the WO3/ITO and ITO/glass boundaries as well as with carbonaceous solid-electrolyte interfacial layers on the WO3 films. Our work provides important new insights into long-term durability of ion-exchange-based devices.

  • 5.
    Aung, Su Htike
    et al.
    Swiss Fed Inst Technol Lausanne EPFL, EPFL SB ISIC LSPM, Inst Chem Sci & Engn, Lab Photomol Sci, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland;Shwebo Univ, Phys Dept, Shwebo 02261, Myanmar;Univ Mandalay, Dept Phys, Mat Res Lab, Mandalay 05032, Myanmar.
    Zhao, Lichen
    Swiss Fed Inst Technol Lausanne EPFL, EPFL SB ISIC LPI, Lab Photon & Interfaces, Inst Chem Sci & Engn, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland;Peking Univ, Dept Phys, State Key Lab Artificial Microstruct & Mesoscop P, Beijing 100871, Peoples R China.
    Nonomura, Kazuteru
    Swiss Fed Inst Technol Lausanne EPFL, EPFL SB ISIC LSPM, Inst Chem Sci & Engn, Lab Photomol Sci, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland.
    Oo, Than Zaw
    Univ Mandalay, Dept Phys, Mat Res Lab, Mandalay 05032, Myanmar.
    Zakeeruddin, Shaik M.
    Swiss Fed Inst Technol Lausanne EPFL, EPFL SB ISIC LPI, Lab Photon & Interfaces, Inst Chem Sci & Engn, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland.
    Vlachopoulos, Nick
    Swiss Fed Inst Technol Lausanne EPFL, EPFL SB ISIC LSPM, Inst Chem Sci & Engn, Lab Photomol Sci, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland.
    Sloboda, Tamara
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Svanström, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Cappel, Ute B.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Hagfeldt, Anders
    Swiss Fed Inst Technol Lausanne EPFL, EPFL SB ISIC LSPM, Inst Chem Sci & Engn, Lab Photomol Sci, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland.
    Graetzel, Michael
    Swiss Fed Inst Technol Lausanne EPFL, EPFL SB ISIC LPI, Lab Photon & Interfaces, Inst Chem Sci & Engn, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland.
    Toward an alternative approach for the preparation of low-temperature titanium dioxide blocking underlayers for perovskite solar cells2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 17, s. 10729-10738Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The anodic electrodeposition method is investigated as an alternative technique for the preparation of a titanium oxide (TiO2) blocking underlayer (UL) for perovskite solar cells (PSCs). Extremely thin Ti-IV-based films are grown from aqueous acidic titanium(III) chloride in an electrochemical cell at room temperature. This precursor layer is converted to the UL (ED-UL), in a suitable state for PSC applications, by undertaking a sintering step at 450 degrees C for half an hour. PSCs with the composition of the light-absorbing material FA(0.85)MA(0.10)Cs(0.05)Pb(I0.87Br0.13)(3) (FA and MA denote the formamidinium and methylammonium cations, respectively) based on the ED-UL are compared with PSCs with the UL of a standard type prepared by the spray-pyrolysis method at 450 degrees C from titanium diisopropoxide bis(acetylacetonate) (SP-UL). We obtain power conversion efficiencies (PCEs) of over 20% for mesoscopic perovskite devices employing both ED-ULs and SP-ULs. Slightly higher fill factor values are observed for ED-UL-based devices. In addition, ED-ULs prepared by the same method have also been applied in planar PSCs, resulting in a PCE exceeding 17%, which is comparable to that for similar PSCs with an SP-UL. The preparation of ED-ULs with a lower sintering temperature, 150 degrees C, has also been examined. The efficiency of a planar PSC incorporating this underlayer was 14%. These results point out to the possibility of applying ED-ULs in flexible planar PSCs in the future.

  • 6.
    Banerjee, Amitava
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Araujo, Rafael B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden.
    Unveiling the thermodynamic and kinetic properties of NaxFe(SO4)2 (x = 0–2): toward a high-capacity and low-cost cathode material2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, s. 17960-17969Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mineral eldfellite, NaFe(SO4)2, was recently proposed as an inexpensive candidate for the next generation of cathode application in Na-based batteries. Employing the density functional theory framework, we have investigated the phase stability, electrochemical properties and ionic diffusion of this eldfellite cathode material. We showed that the crystal structure undergoes a volume shrinkage of ≈8% upon full removal of Na ions with no imaginary frequencies at the Γ point of phonon dispersion. This evokes the stability of the host structure. According to this result, we proposed structural changes to get higher specific energy by inserting two Na ions per redox-active metal. Our calculations indicate NaV(SO4)2 as the best candidate with the capability of reversibly inserting two Na ions per redox center and producing an excellent specific energy. The main bottleneck for the application of eldfellite as a cathode is the high activation energies for the Na+ ion hop, which can reach values even higher than 1 eV for the charged state. This effect produces a low ionic insertion rate.

  • 7.
    Banerjee, Amitava
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Chakraborty, Sudip
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Bromination-induced stability enhancement with a multivalley optical response signature in guanidinium [C(NH2)(3)](+)-based hybrid perovskite solar cells2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 35, s. 18561-18568Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Guanidinium lead iodide (GAPbI(3)) has been synthesized experimentally, but stability remains an issue, which can be modulated by the insertion of bromine (Br) into the system. We have performed a systematic theoretical investigation to see how bromination can tune the stability of GAPbI(3). The optical properties were also determined, and we have found formation enthalpy-based stability in the perovskite systems, which are active in the visible and IR region even after bromine insertion and additionally more active in the IR range with the transition from GAPbI(3) to GAPbBr(3). The spin orbit coupling effect is considered throughout the band structure calculations. The ensemble of the primary and secondary gaps in the half and fully brominated hybrid perovskites leads to the phenomenon of a multipeak response in the optical spectra, which can be subsequently attributed as multivalley optical response behaviour. This multivalley optical behaviour enables the brominated guanidinium-based hybrid perovskites to exhibit broad light harvesting abilities, and this can be perceived as an idea for natural multi-junction solar cells.

  • 8.
    Bhunia, Asamanjoy
    et al.
    Univ Ghent, Ctr Ordered Mat Organomet & Catalysis, Dept Inorgan & Phys Chem, Krijgslaan 281-S3, B-9000 Ghent, Belgium.;Univ Dusseldorf, Inst Anorgan Chem & Strukturchem, D-40204 Dusseldorf, Germany..
    Esquivel, Dolores
    Univ Ghent, Ctr Ordered Mat Organomet & Catalysis, Dept Inorgan & Phys Chem, Krijgslaan 281-S3, B-9000 Ghent, Belgium.;Univ Cordoba, Fac Sci, Dept Organ Chem, Nanochem & Fine Chem Res Inst IUIQFN, Campus Rabanales,Marie Curie Bldg,Ctra Nal 4, E-14071 Cordoba, Spain..
    Dey, Subarna
    Univ Dusseldorf, Inst Anorgan Chem & Strukturchem, D-40204 Dusseldorf, Germany..
    Fernandez-Teran, Ricardo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Goto, Yasutomo
    Toyota Cent Res & Dev Labs Inc, Nagakute, Aichi 4801192, Japan..
    Inagaki, Shinji
    Toyota Cent Res & Dev Labs Inc, Nagakute, Aichi 4801192, Japan..
    Van der Voort, Pascal
    Univ Ghent, Ctr Ordered Mat Organomet & Catalysis, Dept Inorgan & Phys Chem, Krijgslaan 281-S3, B-9000 Ghent, Belgium..
    Janiak, Christoph
    Univ Dusseldorf, Inst Anorgan Chem & Strukturchem, D-40204 Dusseldorf, Germany..
    A photoluminescent covalent triazine framework: CO2 adsorption, light-driven hydrogen evolution and sensing of nitroaromatics2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 35, s. 13450-13457Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly photoluminescent (PL) porous covalent triazine-based framework (PCTF-8) is synthesized from tetra(4-cyanophenyl) ethylene by using trifluoromethanesulfonic acid as the catalyst at room temperature. Due to triazine units in the framework, the PCTF-8 exhibits excellent thermal stability (>400 degrees C). The Brunauer-Emmett-Teller (BET) specific surface area of PCTF-8 is 625 m(2) g(-1) which is lower than the one obtained from the synthesis under Lewis acid conditions (ZnCl2). At 1 bar and 273 K, the PCTF-8 adsorbs a significant amount of CO2 (56 cm(3) g(-1)) and CH4 (17 cm(3) g(-1)) which is highly comparable to nanoporous 1,3,5-triazine frameworks (NOP-1-6, 29-56 cm(3) g(-1)). This nitrogen rich framework exhibits good ideal selectivity (61 : 1 (85% N-2 : 15% CO2) at 273 K, 1 bar). Thus, it can be used as a promising candidate for potential applications in post-combustion CO2 capture and sequestration technologies. In addition, photoluminescence properties as well as the sensing behaviour towards nitroaromatics have been demonstrated. The fluorescence emission intensity of PCTF-8 is quenched by ca. 71% in the presence of 2,4,6-trinitrophenol (TNP). From time-resolved studies, a static quenching behaviour was found. This high photoluminescence property is used for hydrogen evolving organic photocatalysis from water in the presence of a sacrificial electron donor and a cocatalyst.

  • 9.
    Bielecki, Johan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär biofysik.
    Parker, Stewart F.
    Ekanayake, Dharshani
    Rahman, Seikh M. H.
    Borjesson, Lars
    Karlsson, Maths
    Short-range structure of the brownmillerite-type oxide Ba2In2O5 and its hydrated proton-conducting form BaInO3H2014Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, nr 40, s. 16915-16924Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The vibrational spectra and short-range structure of the brownmillerite-type oxide Ba2In2O6 and its hydrated form BaInO3H, are investigated by means of Raman, infrared, and inelastic neutron scattering spectroscopies together with density functional theory calculations. For Ba2In2O6, which may be described as an oxygen deficient perovskite structure with alternating layers of InO6 octahedra and InO4 tetrahedra, the results affirm a short-range structure of Icmm symmetry, which is characterized by random orientation of successive layers of InO4 tetrahedra. For the hydrated, proton conducting, form, BaInO3H, the results suggest that the short-range structure is more complicated than the P4/mbm symmetry that has been proposed previously on the basis of neutron diffraction, but rather suggest a proton configuration close to the lowest energy structure predicted by Martinez et al. [J.-R. Martinez, C. E. Moen, S. Stoelen, N. L. Allan, J. Solid State Chem., 180, 3388, (2007)]. An intense Raman active vibration at 150 cm(-1) is identified as a unique fingerprint of this proton configuration.

  • 10.
    Bielecki, Johan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för cell- och molekylärbiologi, Molekylär biofysik. Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Parker, Stewart F.
    Rutherford Appleton Lab, STFC, ISIS Facil, Didcot OX11 0QX, Oxon, England..
    Mazzei, Laura
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Börjesson, Lars
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Karlsson, Maths
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Structure and dehydration mechanism of the proton conducting oxide Ba2In2O5(H2O)(x)2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 4, s. 1224-1232Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure and dehydration mechanism of the proton conducting oxide Ba2In2O5(H2O)(x) are investigated by means of variable temperature (20-600 degrees C) Raman spectroscopy together with thermal gravimetric analysis and inelastic neutron scattering. At room temperature, Ba2In2O5(H2O)(x) is found to be fully hydrated (x = 1) and to have a perovskite-like structure, which dehydrates gradually with increasing temperature and at around 600 degrees C the material is essentially dehydrated (x approximate to 0.2). The dehydrated material exhibits a brownmillerite structure, which is featured by alternating layers of InO6 octahedra and InO4 tetrahedra. The transition from a perovskite-like to a brownmillerite-like structure upon increasing temperature occurs through the formation of an intermediate phase at ca. 370 degrees C, corresponding to a hydration degree of approximately 50%. The structure of the intermediate phase is similar to the structure of the dehydrated material, but with the difference that it exhibits a non-centrosymmetric distortion of the InO6 octahedra that is not present in the dehydrated material. The dehydration process upon heating is a two-stage mechanism; for temperatures below the hydrated-to-intermediate phase transition, dehydration is characterized by a homogenous release of protons over the entire oxide lattice, whereas above the transition a preferential desorption of protons originating in the nominally tetrahedral layers is observed. Furthermore, our spectroscopic results point towards the co-existence of two structural phases, which relate to the two lowest-energy proton configurations in the material. The relative contributions of the two proton configurations depend on how the sample is hydrated.

  • 11.
    Choudhury, Sneha
    et al.
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Methods Mat Dev, Albert Einstein Str 15, D-12489 Berlin, Germany;Free Univ Berlin, Inst Chem & Biochem, Fabeckstr 36a, D-14195 Berlin, Germany.
    Kiendl, Benjamin
    Univ Wurzburg, Inst Organ Chem, D-97074 Wurzburg, Germany.
    Ren, Jian
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Methods Mat Dev, Albert Einstein Str 15, D-12489 Berlin, Germany;Free Univ Berlin, Dept Phys, Arnimallee 14, D-14195 Berlin, Germany.
    Gao, Fang
    Fraunhofer Inst Appl Solid State Phys IAF, Tullastr 72, D-79108 Freiburg, Germany;Max Planck Inst Mikrostrukturphys, Weinberg 2, D-06120 Halle, Germany.
    Knittel, Peter
    Fraunhofer Inst Appl Solid State Phys IAF, Tullastr 72, D-79108 Freiburg, Germany.
    Nebel, Christoph
    Fraunhofer Inst Appl Solid State Phys IAF, Tullastr 72, D-79108 Freiburg, Germany.
    Venerosy, Amelie
    CEA, LIST, Diamond Sensors Lab, F-91191 Gif Sur Yvette, France.
    Girard, Hugues
    CEA, LIST, Diamond Sensors Lab, F-91191 Gif Sur Yvette, France.
    Arnault, Jean-Charles
    CEA, LIST, Diamond Sensors Lab, F-91191 Gif Sur Yvette, France.
    Krueger, Anke
    Univ Wurzburg, Inst Organ Chem, D-97074 Wurzburg, Germany.
    Larsson, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Petit, Tristan
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Methods Mat Dev, Albert Einstein Str 15, D-12489 Berlin, Germany.
    Combining nanostructuration with boron doping to alter sub band gap acceptor states in diamond materials2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 34, s. 16645-16654Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Diamond is a promising metal-free photocatalyst for nitrogen and carbon dioxide reduction in aqueous environment owing to the possibility of emitting highly reducing solvated electrons. However, the wide band gap of diamond necessitates the use of deep UV to trigger a photochemical reaction. Boron doping introduces acceptor levels within the band gap of diamonds, which may facilitate visible-light absorption through defect-based transitions. In this work, unoccupied electronic states from different boron-doped diamond materials, including single crystal, polycrystalline film, diamond foam, and nanodiamonds were probed by soft X-ray absorption spectroscopy at the carbon K edge. Supported by density functional theory calculations, we demonstrate that boron close to the surfaces of diamond crystallites induce acceptor levels in the band gap, which are dependent on the diamond morphology. Combining boron-doping with morphology engineering, this work thus demonstrates that electron acceptor states within the diamond band gap can be controlled.

  • 12. Dwibedi, D.
    et al.
    Barros Neves de Araujo, Rafael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Chakraborty, Sidip
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Shanbogh, P. P.
    Sundaram, N. G.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Barpanda, P.
    Na2.44Mn1.79(SO4 )3: A new member of alluaudite family of insertion compounds for sodium ion batteries2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488Artikkel i tidsskrift (Annet vitenskapelig)
  • 13. Dwibedi, Debasmita
    et al.
    Araujo, Rafael B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Chakraborty, Sudip
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Shanbogh, Pradeep P.
    Sundaram, Nalini G.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Barpanda, Prabeer
    Na2.44Mn1.79(SO4)(3): a new member of the alluaudite family of insertion compounds for sodium ion batteries2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 36, s. 18564-18571Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sodium-ion batteries have been extensively pursued as economic alternatives to lithium-ion batteries. Investigating the polyanion chemistry, alluaudite structured Na2Fe2II(SO4)(3) has been recently discovered as a 3.8 V positive electrode material (Barpanda et al., Nature Commun., 5: 4358, 2014). Registering the highest ever Fe-III/Fe-II redox potential (vs. Na/Na+) and formidable energy density, it has opened up a new polyanion family for sodium batteries. Exploring the alluaudite family, here we report isotypical Na2+2xMn2-xII(SO4)(3) (x = 0.22) as a novel high-voltage cathode material for the first time. Following low-temperature (ca. 350 degrees C) solid-state synthesis, the structure of this new alluaudite compound has been solved adopting a monoclinic framework (s.g. C2/c) showing antiferromagnetic ordering at 3.4 K. Synergising experimental and ab initio DFT investigation, Na2+2xMn2-xII(SO4)(3) has been found to be a potential high-voltage (ca. 4.4 V) cathode material for sodium batteries.

  • 14.
    Ebadi, Mahsa
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Marchiori, Cleber
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Mindemark, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Araujo, Carlos Moyses
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Assessing structure and stability of polymer/lithium-metal interfaces from first-principles calculations2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 14, s. 8394-8404Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Solid polymer electrolytes (SPEs) are promising candidates for Li metal battery applications, but the interface between these two categories of materials has so far been studied only to a limited degree. A better understanding of interfacial phenomena, primarily polymer degradation, is essential for improving battery performance. The aim of this study is to get insights into atomistic surface interaction and the early stages of solid electrolyte interphase formation between ionically conductive SPE host polymers and the Li metal electrode. A range of SPE candidates are studied, representative of major host material classes: polyethers, polyalcohols, polyesters, polycarbonates, polyamines and polynitriles. Density functional theory (DFT) calculations are carried out to study the stability and the electronic structure of such polymer/Li interfaces. The adsorption energies indicated a stronger adhesion to Li metal of polymers with ester/carbonate and nitrile functional groups. Together with a higher charge redistribution, a higher reactivity of these polymers is predicted as compared to the other electrolyte hosts. Products such as alkoxides and CO are obtained from the degradation of ester- and carbonate-based polymers by AIMD simulations, in agreement with experimental studies. Analogous to low-molecular-weight organic carbonates, decomposition pathways through C-carbonyl-O-ethereal and C-ethereal-O-ethereal bond cleavage can be assumed, with carbonate-containing fragments being thermodynamically favorable.

  • 15.
    Etman, Ahmed S.
    et al.
    Stockholms Universitet.
    Asfaw, Habtom D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Yuan, Ning
    Stockholm University and SLU.
    Li, Jian
    Peking University, China.
    Zhou, Zhengyang
    Peking University.
    Peng, Fei
    Stockholm University.
    Persson, Ingmar
    Swedish University of Agricultural Sciences.
    Zou, Xiaodong
    Stockholm University.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Sun, Junliang
    Stockholm University and Peking University.
    A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 46, s. 17988-18001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The synthesis of two dimensional (2D) materials from transition metal oxides, chalcogenides, and carbides mostly involve multiple exfoliation steps in which hazardous solvents and reagents are used. In this study, hydrated vanadium pentoxide (V2O5[middle dot]nH2O) nanosheets with a thickness of a few nanometers were prepared via a facile environmentally friendly water based exfoliation technique. The exfoliation process involved refluxing the precursor, vanadium dioxide (VO2(B)), in water for a few days at 60 [degree]C. The proposed exfoliation mechanism is based on the intercalation/insertion of water molecules into the VO2(B) crystals and the subsequent cleavage of the covalent bonds holding the layers of VO2(B) together. The thermal and chemical analyses showed that the approximate chemical composition of the nanosheets is H0.4V2O5[middle dot]0.55H2O, and the percentage of VV content to that of VIV in the nanosheets is about 80(3)% to 20(3)%. The exfoliated aqueous suspension of the V2O5[middle dot]0.55H2O nanosheets was successfully deposited onto multi-walled carbon nanotube (MW-CNT) paper to form free-standing electrodes with a thickness of the V2O5[middle dot]0.55H2O layer ranging between 45 and 4 [small mu ]m. A series of electrochemical tests were conducted on the electrodes to determine the cyclability and rate capability of lithium insertion into V2O5[middle dot]0.55H2O nanosheets. The electrodes with the thinnest active material coating ([similar]4 [small mu ]m) delivered gravimetric capacities of up to 480 and 280 mA h g-1 when cycled at current densities of 10 and 200 mA g-1, respectively.

  • 16.
    Gao, Jiajia
    et al.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Yang, Wenxing
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    El-Zohry, Ahmed M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Prajapati, Govind Kumar
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Fang, Yuan
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Dai, Jing
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Hao, Yan
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Leandri, Valentina
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Svensson, Per H.
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden;RISE Surface Proc Formulat, Forskargatan 20j, SE-15136 Sodertalje, Sweden.
    Furao, Istvan
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Lund, Torben
    Roskilde Univ, Dept Sci & Environm, DK-4000 Roskilde, Denmark.
    Kloo, Lars
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, SE-10044 Stockholm, Sweden.
    Light-induced electrolyte improvement in cobalt tris(bipyridine)-mediated dye-sensitized solar cells2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 33, s. 19495-19505Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lithium-ion-free tris(2,2 '-bipyridine) Co(ii/iii)-mediated electrolytes have previously been proposed for long-term stable dye-sensitized solar cells (DSSCs). Such redox systems also offer an impressive DSSC performance improvement under light soaking exposure, manifested by an increase in photocurrent and fill factor without the expense of decreasing photovoltage. Kinetic studies show that charge transfer and ion diffusion at the electrode/electrolyte interface are improved due to the light exposure. Control experiments reveal that the light effect is unambiguously associated with electrolyte components, [Co(bpy)(3)](3+) and the Lewis-base additive tert-butylpyridine (TBP). Electrochemical and spectroscopic investigation of the [Co(bpy)(3)](3+)/TBP mixtures points out that the presence of TBP, which retards the electrolyte diffusion, however causes an irreversible redox reaction of [Co(bpy)(3)](3+) upon light exposure that improves the overall conductivity. This discovery not only provides a new strategy to mitigate the typical J(sc)-V-oc trade-off in Co(ii/iii)-mediated DSSCs but also highlights the importance of investigating the photochemistry of a photoelectrochemical system.

  • 17.
    Iakunkov, Artem
    et al.
    Umea Univ, Dept Phys, S-90187 Umea, Sweden.
    Sun, Jinhua
    Umea Univ, Dept Phys, S-90187 Umea, Sweden.
    Rebrikova, Anastasia
    Moscow MV Lomonosov State Univ, Dept Chem, Leninskie Gory 1-3, Moscow 119991, Russia.
    Korobov, Mikhail
    Moscow MV Lomonosov State Univ, Dept Chem, Leninskie Gory 1-3, Moscow 119991, Russia.
    Klechikov, Alexey
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik. Umea Univ, Dept Phys, S-90187 Umea, Sweden.
    Vorobiev, Alexei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Boulanger, Nicolas
    Umea Univ, Dept Phys, S-90187 Umea, Sweden.
    Talyzin, Alexandr V.
    Umea Univ, Dept Phys, S-90187 Umea, Sweden.
    Swelling of graphene oxide membranes in alcohols: effects of molecule size and air ageing2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 18, s. 11331-11337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Swelling of Hummers graphene oxide (HGO) membranes in a set of progressively longer liquid alcohols (methanol to 1-nonanol) was studied using synchrotron radiation XRD after air ageing over prolonged periods of time. Both precursor graphite oxides and freshly prepared HGO membranes were found to swell in the whole set of nine liquid alcohols with an increase of interlayer spacing from approximate to 7 angstrom (solvent free) up to approximate to 26 angstrom (in 1-nonanol). A pronounced effect of ageing on swelling in alcohols was found for HGO membranes stored in air. The HGO membranes aged for 0.5-1.5 years show progressively slower swelling kinetics, a non-monotonic decrease of saturated swelling in some alcohols and complete disappearance of swelling for alcohol molecules larger than hexanol. Moreover, the HGO membranes stored under ambient conditions for 5 years showed a nearly complete absence of swelling in all alcohols but preserved swelling in water. In contrast, precursor graphite oxide powder showed unmodified swelling in alcohols even after 4 years of ageing. Since the swelling defines the size of permeation channels, the ageing effect is one of the important parameters which could explain the strong variation in reported filtration/separation properties of GO membranes. The time and conditions of air storage require standardization for better reproducibility of results related to performance of GO membranes in various applications. The ageing of GO membranes can be considered not only as a hindrance/degradation for certain applications, but also as a method to tune the swelling properties of HGO membranes for better selectivity in sorption of solvents and for achieving better selective permeability.

  • 18.
    Jain, Sagar Motilal
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Philippe, Bertrand
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Park, Byung-Wook
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Vapor phase conversion of PbI2 to CH3NH3PbI3: spectroscopic evidence for formation of an intermediate phase2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 7, s. 2630-2642Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The formation of CH3NH3PbI3 (MAPbI(3)) from its precursors is probably the most significant step in the control of the quality of this semiconductor perovskite material, which is highly promising for photovoltaic applications. Here we investigated the transformation of spin coated PbI2 films to MAPbI(3) using a reaction with MAI in vapor phase, referred to as vapor assisted solution process (VASP). The presence of a mesoporous TiO2 scaffold on the substrate was found to speed up reaction and led to complete conversion of PbI2, while reaction on glass substrates was slower, with some PbI2 remaining even after prolonged reaction time. Based on data from UV-visible spectroscopy, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, the formation of an X-ray amorphous intermediate phase is proposed, which is identified by an increasing absorption from 650 to 500 nm in the absorption spectrum. This feature disappears upon long reaction times for films on planar substrates, but persists for films on mesoporous TiO2. Poor solar cell performance of planar VASP prepared devices was ascribed to PbI2 remaining in the film, forming a barrier between the perovskite layer and the compact TiO2/FTO contact. Good performance, with efficiencies up to 13.3%, was obtained for VASP prepared devices on mesoporous TiO2.

  • 19.
    Jiang, Roger
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    The Impact of Non-Uniform Photogeneration on Mass Transport in Dye-Sensitised Solar Cells2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 22, s. 10264-10276Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Following the introduction of cobalt(II/III)tris(2,2'-bipyridyl)-based redox mediators, dye-sensitised solar cells (DSSCs) have greatly advanced in power conversion efficiency (PCE). However, significant limiting factors include the fast electron recombination and slow mass transport of the oxidised redox mediator ([Co(bipy)(3)](3+)). In this work, the effect of non-uniform photogeneration on the mass transport of [Co(bipy)(3)](3+) through an electrolyte-infiltrated mesoporous TiO2 film was investigated. Different illumination conditions were used to control the photogeneration profile and the subsequent spatial distribution of [Co(bipy)(3)](3+) throughout the TiO2 film. They included parameters such as the light intensity, substrate-electrode/electrolyte-electrode (SE/EE) illumination direction, wavelength, and TiO2 photoanode thickness. Using large and small optical perturbation photocurrent transients, electron recombination kinetics with [Co(bipy)(3)](3+) were analysed in the time domain. Importantly, strong SE-absorption was shown to significantly contribute to the gradual depletion of [Co(bipy)(3)](3+) at the counter electrode, along with an increased film thickness and light intensity, resulting in excess recombination with [Co(bipy)(3)](3+) on the 10(-2)-1 s timescale. Furthermore, charge extraction current decay transients showed that a substantial amount of [Co(bipy)(3)](3+) can accumulate inside the TiO2 film, resulting in significant recombination at the collecting fluorine-doped tin oxide (FTO) contact on the 10(-3)-10(-2) s timescale. The sub-linear scaling of recombination with light intensity leads to deviating trends in charge extraction and electron transport measurements. Mass transport limitations and recombination losses at the FTO can be significantly reduced by maximising light absorption from the EE-side, which can increase PCE and reduce J-V hysteresis.

  • 20.
    Jorner, Kjell
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Dreos, Ambra
    Chalmers, Dept Chem & Chem Engn, Kemigarden 4, SE-41296 Gothenburg, Sweden..
    Emanuelsson, Rikard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    El Bakouri, Ouissam
    Univ Girona, Dept Quim, IQCC, Campus Montilivi, Girona 17003, Spain..
    Fernández Galván, Ignacio
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Teoretisk kemi. Uppsala Univ, UC3, Box 523, SE-75120 Uppsala, Sweden..
    Borjesson, Karl
    Chalmers, Dept Chem & Chem Engn, Kemigarden 4, SE-41296 Gothenburg, Sweden.;Univ Gothenburg, Dept Chem & Mol Biol, Kemigarden 4, SE-41296 Gothenburg, Sweden..
    Feixas, Ferran
    Univ Girona, Dept Quim, IQCC, Campus Montilivi, Girona 17003, Spain..
    Lindh, Roland
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Teoretisk kemi. Uppsala Univ, UC3, Box 523, SE-75120 Uppsala, Sweden..
    Zietz, Burkhard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Moth-Poulsen, Kasper
    Chalmers, Dept Chem & Chem Engn, Kemigarden 4, SE-41296 Gothenburg, Sweden..
    Ottosson, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC.
    Unraveling factors leading to efficient norbornadiene-quadricyclane molecular solar-thermal energy storage systems2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 24, s. 12369-12378Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Developing norbornadiene-quadricyclane (NBD-QC) systems for molecular solar-thermal (MOST) energy storage is often a process of trial and error. By studying a series of norbornadienes (NBD-R-2) doubly substituted at the C7-position with R = H, Me, and iPr, we untangle the interrelated factors affecting MOST performance through a combination of experiment and theory. Increasing the steric bulk along the NBD-R-2 series gave higher quantum yields, slightly red-shifted absorptions, and longer thermal lifetimes of the energy-rich QC isomer. However, these advantages are counterbalanced by lower energy storage capacities, and overall R = Me appears most promising for short-term MOST applications. Computationally we find that it is the destabilization of the NBD isomer over the QC isomer with increasing steric bulk that is responsible for most of the observed trends and we can also predict the relative quantum yields by characterizing the S-1/S-0 conical intersections. The significantly increased thermal half-life of NBD-iPr(2) is caused by a higher activation entropy, highlighting a novel strategy to improve thermal half-lives of MOST compounds and other photo-switchable molecules without affecting their electronic properties. The potential of the NBD-R-2 compounds in devices is also explored, demonstrating a solar energy storage efficiency of up to 0.2%. Finally, we show how the insights gained in this study can be used to identify strategies to improve already existing NBD-QC systems.

  • 21.
    Kan, Zhipeng
    et al.
    Ist Italiano Tecnol, Ctr Nano Sci & Technol PoliMi, Via Giovanni Pascoli 70-3, I-20133 Milan, Italy..
    Colella, Letizia
    Politecn Milan, Dipartimento Chim Mat & Ing Chim G Natta, Piazza Leonardo da Vinci 32, I-20133 Milan, Italy.;Osserv Astron Brera, INAF, Via Bianchi 46, I-23807 Merate, Italy..
    Canesi, Eleonora V.
    Ist Italiano Tecnol, Ctr Nano Sci & Technol PoliMi, Via Giovanni Pascoli 70-3, I-20133 Milan, Italy.;Politecn Milan, Dipartimento Chim Mat & Ing Chim G Natta, Piazza Leonardo da Vinci 32, I-20133 Milan, Italy..
    Vorobiev, Alexei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Skrypnychuk, Vasyl
    Umea Univ, Nanoengineered Mat & Organ Elect Lab, Umea, Sweden..
    Terraneo, Giancarlo
    Ist Italiano Tecnol, Ctr Nano Sci & Technol PoliMi, Via Giovanni Pascoli 70-3, I-20133 Milan, Italy.;Politecn Milan, Dipartimento Chim Mat & Ing Chim G Natta, Piazza Leonardo da Vinci 32, I-20133 Milan, Italy..
    Barbero, David R.
    Umea Univ, Nanoengineered Mat & Organ Elect Lab, Umea, Sweden..
    Bertarelli, Chiara
    Ist Italiano Tecnol, Ctr Nano Sci & Technol PoliMi, Via Giovanni Pascoli 70-3, I-20133 Milan, Italy.;Politecn Milan, Dipartimento Chim Mat & Ing Chim G Natta, Piazza Leonardo da Vinci 32, I-20133 Milan, Italy..
    MacKenzie, Roderick C. I.
    Univ Nottingham, Fac Engn, Univ Pk, Nottingham NG7 2RD, England..
    Keivanidis, Panagiotis E.
    Cyprus Univ Technol, Dept Mech Engn & Mat Sci & Engn, 45 Kitiou Kyprianou Str, CY-3041 Limassol, Cyprus..
    Charge transport control via polymer polymorph modulation in ternary organic photovoltaic composites2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 4, s. 1195-1201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The control on the charge transport properties of ternary organic photovoltaic P3HT : PCBM : QBT devices is enabled by modulating the distribution of P3HT polymorphs in the device photoactive layers. Negligible amounts of QBT induce striking modifications in the P3HT lamellar stacking direction, forming both densely packed and non-densely packed P3HT chains. The former reduce the charge carrier recombination rate, enabling an increased fill factor and short-circuit device photocurrent.

  • 22.
    Krishna, Anurag
    et al.
    Nanyang Technol Univ, Interdisciplinary Grad Sch, Energy Res Inst, Singapore 639798, Singapore..
    Sabba, Dharani
    Energy Res Inst NTU ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore..
    Yin, Jun
    Nanyang Technol Univ, Div Phys & Appl Phys, 21 Nanyang Link, Singapore 637371, Singapore..
    Bruno, Annalisa
    Energy Res Inst NTU ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore..
    Antila, Liisa J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Soci, Cesare
    Nanyang Technol Univ, Div Phys & Appl Phys, 21 Nanyang Link, Singapore 637371, Singapore..
    Mhaisalkar, Subodh
    Energy Res Inst NTU ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore.;Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore..
    Grimsdale, Andrew C.
    Energy Res Inst NTU ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore.;Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore..
    Facile synthesis of a hole transporting material with a silafluorene core for efficient mesoscopic CH3NH3PbI3 perovskite solar cells2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 22, s. 8750-8754Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel electron-rich small-molecule, 4,4'-(5,5-dihexyl-5H-dibenzo[b,d]silole-3,7-diyl)bis(N,N-bis(4-methoxyphenyl)aniline) (S101), containing silafluorene as the core with arylamine side groups, has been synthesized via a short efficient route. When S101 was incorporated into a CH3NH3PbI3 perovskite solar cell as a hole transporting material (HTM), a short circuit photocurrent density (J(sc)) of 18.9 mA cm(-2), an open circuit voltage (V-oc) of 0.92 V, and a fill factor (FF) of 0.65 contributing to an overall power conversion efficiency (PCE) of similar to 11% which is comparable to the PCE obtained using the current state-of-the-art HTM 2,2',7,7'-tetrakis(N,N'-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) (eta = 12.3%) were obtained. S101 is thus a promising HTM with the potential to replace the expensive spiro-OMeTAD due to its comparable performance and much simpler and less expensive synthesis route.

  • 23.
    Lal, Sohan
    et al.
    Indian Inst Technol, Dept Chem, Bombay 400076, Maharashtra, India..
    Mallick, Lovely
    Indian Inst Technol, Dept Mech Engn, Bombay 400076, Maharashtra, India..
    Rajkumar, Sundaram
    Indian Inst Technol, Dept Chem, Bombay 400076, Maharashtra, India..
    Oommen, Oommen P.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi. Indian Inst Technol, Dept Chem, Bombay 400076, Maharashtra, India..
    Reshmi, Sasidharakurup
    Vikram Sarabhai Space Ctr, PCM Ent, Polymers & Special Chem Grp, Thiruvananthapuram 695022, Kerala, India..
    Kumbhakarna, Neeraj
    Indian Inst Technol, Dept Mech Engn, Bombay 400076, Maharashtra, India..
    Chowdhury, Arindrajit
    Indian Inst Technol, Dept Mech Engn, Bombay 400076, Maharashtra, India..
    Namboothiri, Irishi N. N.
    Indian Inst Technol, Dept Chem, Bombay 400076, Maharashtra, India..
    Synthesis and energetic properties of high-nitrogen substituted bishomocubanes2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 44, s. 22118-22128Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Synthesis, thermodynamic characterization, and energetic properties of three novel high-nitrogen bishomocubane-based compounds DADMBHC, DTetzBHC and DPTrizDMBHC are reported here. These compounds have higher heats of formation (HoFs) and higher energy densities as compared to traditional hydrocarbon fuels. Densities, gas phase HoF and their optimized molecular structure geometries were calculated with various levels of theory. In general, the calculated HoFs of these compounds turn out to be extremely high. Ballistic properties such as vacuum specific impulse and density vacuum specific impulse were calculated using the NASA Chemical Equilibrium and Applications utility. Propulsive properties were compared with liquid bipropellants (RP1) and solid propellants (AP) and explosive properties were compared with RDX. The density specific impulse demonstrated an improvement of 35 s for DADMBHC and DTetzBHC over standard liquid hydrocarbon HTPB, thus showing promise as possible monomers to replace HTPB as a fuel-binder. The density specific impulses of these compounds were also found to be significantly higher than that of RP1, e.g. that of DADMBHC was found to be higher by 84 s, making them potentially good candidates as propellants for use under volume-limited conditions. The detonation properties showed that these compounds have low potential as explosives. TGA, coupled with IR spectroscopy, revealed that DADMBHC and DPTrizDMBHC evaporate readily while DTetzBHC decomposes partially.

  • 24.
    Li, Yuhan
    et al.
    Northeast Normal Univ, Inst Funct Mat, Fac Chem, Changchun 130024, Jilin, Peoples R China.;Beihua Univ, Coll Chem & Biol, Jilin 132013, Jilin, Peoples R China..
    Sun, Weiwei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Liang, Jing
    Northeast Normal Univ, Inst Funct Mat, Fac Chem, Changchun 130024, Jilin, Peoples R China.;Northeast Normal Univ, Natl & Local United Engn Lab Power Battery, Changchun 130024, Jilin, Peoples R China..
    Sun, Hao
    Northeast Normal Univ, Inst Funct Mat, Fac Chem, Changchun 130024, Jilin, Peoples R China.;Northeast Normal Univ, Natl & Local United Engn Lab Power Battery, Changchun 130024, Jilin, Peoples R China..
    Di Marco, Igor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Ni, Lei
    Beihua Univ, Coll Chem & Biol, Jilin 132013, Jilin, Peoples R China..
    Tang, Shuwei
    Northeast Normal Univ, Inst Funct Mat, Fac Chem, Changchun 130024, Jilin, Peoples R China.;Northeast Normal Univ, Natl & Local United Engn Lab Power Battery, Changchun 130024, Jilin, Peoples R China..
    Zhang, Jingping
    Northeast Normal Univ, Inst Funct Mat, Fac Chem, Changchun 130024, Jilin, Peoples R China..
    Understanding the electrochemical properties of A(2)MSiO(4) (A = Li and Na; M = Fe, Mn, Co and Ni) and the Na doping effect on Li2MSiO4 from first-principles calculations2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 44, s. 17455-17463Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To explore the feasibility of regarding silicate materials as sustainable cathode materials for rechargeable Na ion batteries, the voltage plateaus, cycling stabilities, electrical conductivities and ionic conductivities of Li2MSiO4 and Na2MSiO4 (M = Fe, Mn, Co and Ni) are investigated by first principles calculations. The calculated electrochemical performance of silicate materials gives reasonable explanations for the poor capacity retention of Li2MnSiO4 as well as the reason why Li2FeSiO4 and Li2CoSiO4 exchange only one Li ion per formula unit. In comparison with Na2MSiO4, Li2MSiO4 presents higher voltage and better cycling stability. However, Na2MSiO4 displays higher electrical and ionic conductivities. Moreover, Na2NiSiO4 also presents significant potential for application as a good cathode material for Na ion batteries, as it can deliver high voltage and reversibly exchange 1.5 Li ions per formula unit. Furthermore, to make full use of the advantages of Li2MSiO4 and Na2MSiO4, a Na doped Li1.5Na0.5MSiO4 system is explored as well. The results suggest that Na doping can improve the electronic and ionic conductivities of Li2MSiO4 materials and simultaneously maintain the voltage and cycling stability. Therefore, Na ion doping should be an effective methodology to improve the performance of Li2MSiO4 cathode materials.

  • 25.
    Liu, Aijie
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Tai, Cheuk-Wai
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Hola, Katerina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Tian, Haining
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hollow polymer dots: nature-mimicking architecture for efficient photocatalytic hydrogen evolution reaction2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 9, s. 4797-4803Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mimicking nature is always beneficial for improving the performance of artificial systems. Artificial photosynthesis for hydrogen production is one of the examples, where we can derive significant inspiration from nature. In this study, polymer dots (Pdots) prepared using photoactive polymer PFODTBT and amphiphilic co-polymer under ultra-sonication exhibited a hollow structure mimicking a photosynthetic bacterial, which was highly beneficial for hydrogen evolution. A systematic study of this structure showed that the polymer shell acts as a biological membrane that maintains a slightly higher pH inside the cavity (pH 0.4) compared to the bulk solution. More importantly, a fast proton diffusion across the porous polymer shell was detected. The photocatalytic activity of hollow nanostructure shows 50 times enhancement of initial hydrogen evolution reaction (HER) rate as compared to solid nanoparticles. Further optimization of the photocatalytic performance was achieved by verifying the decrease in Pdots size from 90 nm to 50 nm, showing a significant increase in the photocatalytic performance of the system. This study reveals nature-mimicking hollow Pdots with porous shells as can be a type of promising photocatalysts in the application of solar energy conversion and storage.

  • 26.
    Liu, Chenjuan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Qiu, Zhen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Brant, William
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Ma, Yue
    Northwestern Polytechnical University.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Zhu, Jie-Fang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    A free standing Ru–TiC nanowire array/carbon textile cathode with enhanced stability for Li–O2 batteries2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, s. 23659-23668Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The instability of carbon cathode materials is one of the key problems that hinder the development of lithium–air/lithium–oxygen (Li–O2) batteries. In this contribution, a type of TiC-based cathode is developed as a suitable alternative to carbon based cathodes, and its stability with respect to its surface properties is investigated. Here, a free-standing TiC nanowire array cathode was in situ grown on a carbon textile, covering its exposed surface. The TiC nanowire array, via deposition with Ru nanoparticles, showed enhanced oxygen reduction/evolution activity and cyclability, compared to the one without Ru modification. The battery performance of the Li–O2cells with Ru–TiC was investigated by using in operando synchrotron radiation powder X-ray diffraction (SR-PXD) during a full cycle. With the aid of surface analysis, the role of the cathode substrate and surface modification is demonstrated. The presented results are a further step toward a wise design of stable cathodes for Li–O2 batteries.

  • 27.
    Liu, Chenjuan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tai, Cheuk-Wai
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Valvo, Mario
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Zhu, Jiefang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Dalian Univ Technol, State Key Lab Fine Chem, Dalian 116024, Peoples R China.
    3-D binder-free graphene foam as cathode for high capacity Li-O2 batteries2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 25, s. 9767-9773Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    To provide energy densities higher than those of conventional Li-ion batteries, a Li–O2 battery requires a cathode with high surface area to host large amounts of discharge product Li2O2. Therefore, reversible formation of discharge products needs to be investigated in Li–O2 cells containing high surface area cathodes. In this study, a binder-free oxygen electrode consisting of a 3-D graphene structure on aluminum foam, with a high defect level (ID/IG = 1.38), was directly used as the oxygen electrode in Li– O2 batteries, delivering a high capacity of about 9 *104 mA h g-1 (based on the weight of graphene) at the first full discharge using a current density of 100 mA ggraphene-1 . This performance is attributed to the 3-D porous structure of graphene foam providing both an abundance of available space for the deposition of discharge products and a high density of reactive sites for Li–O2 reactions. Furthermore, the formation of discharge products with different morphologies and their decomposition upon charge were observed by SEM. Some nanoscaled LiOH particles embedded in the toroidal Li2O2 were detected by XRD and visualized by TEM. The amount of Li2O2 formed at the end of discharge was revealed by a titration method combined with UV-Vis spectroscopy analysis. 

  • 28.
    Liu, Jianhua
    et al.
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China.
    Zhou, Qisen
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China.
    Kyi Thein, Nan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Mandalay Univ, Res Lab, Dept Phys Mat Sci, Mandalay, Myanmar.
    Tian, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Jia, Donglin
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China.
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Zhang, Xiaoliang
    Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China.
    In situ growth of perovskite stacking layers for high-efficiency carbon-based hole conductor free perovskite solar cells2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 22, s. 13777-13786Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interfacial properties between a perovskite layer and carbon electrode are critical for the photovoltaic performance of carbon electrode-based perovskite solar cells (PSCs). Herein, a methylammonium lead mixed halide (MAPbIxBr3−x) perovskite layer is in situ grown on the top of a methylammonium lead iodide (MAPbI3) perovskite layer forming a MAPbI3/MAPbIxBr3−x perovskite stacking structure (PSS) to improve the interfacial properties at the perovskite/carbon electrode interface. The charge carrier dynamics in both the perovskite and the PSC device induced by the MAPbIxBr3−x perovskite stacking layer are studied using extensive characterization. The charge interfacial recombination at the perovskite/carbon electrode interface is significantly diminished using the PSS within the PSC, resulting in largely improved charge extraction and therefore high photovoltaic performance. The PSS-based PSC shows a power conversion efficiency of up to 16.2% (increased by 43% compared with that of a conventional MAPbI3-based PSC), which is among the highest efficiencies of carbon electrode-based hole conductor free PSCs. Meanwhile, the PSS-based PSC also exhibits good stability under both continuous illumination and storage under dark conditions. This work may provide a new avenue to fine tune the interfacial properties of carbon electrode-based PSCs for further improving their photovoltaic performance.

  • 29. Liu, Peng
    et al.
    Xu, Bo
    Karlsson, Karl Martin
    Zhang, Jinbao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Vlachopoulos, Nick
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Sun, Licheng
    Kloo, Lars
    The combination of a new organic D-pi-A dye with different organic hole-transport materials for efficient solid-state dye-sensitized solar cells2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 8, s. 4420-4427Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new organic donor-pi-acceptor sensitizer MKA253 has been applied for highly efficient solid-state dye-sensitized solar cells (ssDSSCs). Using 2,2',7,7'-tetrakis(N,N-di-pi-methoxyphenyl-amine) 9,9'-spirobifluorene (Spiro-OMeTAD) as the hole transport material (HTM), an excellent power conversion efficiency of 6.1% was recorded together with a high short-circuit current of 12.4 mA cm(-2) under standard AM 1.5G illumination (100 mW cm(-2)). Different combinations of dyes and HTMs have also been investigated in the ssDSSC device. The results showed that small molecule HTM based devices suffer from comparably high electron recombination losses, thus causing low open-circuit voltage. In addition, photo-induced absorption (PIA) spectroscopy showed that the small-molecule HTMs lead to more efficient dye regeneration in comparison with Spiro-OMeTAD, despite a lower thermodynamic driving force. The results of this study also show that optimized energy levels for the dye-HTMs could be a vital factor for highly efficient ssDSSCs.

  • 30.
    Muduli, Subas Kumar
    et al.
    Energy Res Inst NTU, Res Techno Plaza,50 Nanyang Dr, Singapore 637553, Singapore..
    Varrla, Eswaraiah
    Energy Res Inst NTU, Res Techno Plaza,50 Nanyang Dr, Singapore 637553, Singapore.;SRM Univ, Dept Phys & Nanotechnol, SRM Res Inst, Madras 603203, Tamil Nadu, India..
    Xu, You
    Nanyang Technol Univ, Sch Chem & Biomed Engn, 62 Nanyang Dr, Singapore 637459, Singapore..
    Kulkarni, Sneha Avinash
    Energy Res Inst NTU, Res Techno Plaza,50 Nanyang Dr, Singapore 637553, Singapore..
    Katre, Ankita
    CEA Grenoble, LITEN, 17 Rue Martyrs, F-38054 Grenoble 9, France..
    Chakraborty, Sudip
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Chen, Shi
    Nanyang Technol Univ, Sch Phys & Math Sci, Div Phys & Appl Phys, 21 Nanyang Link, Singapore 637371, Singapore..
    Sum, Tze Chien
    Nanyang Technol Univ, Sch Phys & Math Sci, Div Phys & Appl Phys, 21 Nanyang Link, Singapore 637371, Singapore..
    Xu, Rong
    Nanyang Technol Univ, Sch Chem & Biomed Engn, 62 Nanyang Dr, Singapore 637459, Singapore..
    Mathews, Nripan
    Energy Res Inst NTU, Res Techno Plaza,50 Nanyang Dr, Singapore 637553, Singapore.;Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore..
    Evolution of hydrogen by few-layered black phosphorus under visible illumination2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 47, s. 24874-24879Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recently, a new class of two-dimensional black phosphorus (BP) with a visible direct band gap is predicted as a potential candidate for photo-catalysis applications. Here, we present the first experimental evidence of hydrogen (H-2) evolution from aqueous solution by using BP (nanosheets and nanoparticles) under visible light illumination. Our experimental results describe that liquid phase exfoliated BP nanosheets and BP nanoparticles exhibit suitable energy level alignments for electron transfer and further proton reduction reactions in the solution under visible light illumination. Density functional theory (DFT) calculations predict that the H-2 evolution activity of bilayer BP is independent of edge or center positions, which is unique in BP as compared to those of other 2D materials.

  • 31.
    Park, Byung-wook
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Philippe, Bertrand
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Jain, Sagar M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Zhang, Xiaoliang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala Univ, Dept Chem, Angstrom Lab, Inorgan Chem, SE-75120 Uppsala, Sweden..
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Zietz, Burkhard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Uppsala Univ, Dept Chem, Angstrom Lab, Phys Chem, SE-75120 Uppsala, Sweden..
    Chemical engineering of methylammonium lead iodide/bromide perovskites: tuning of opto-electronic properties and photovoltaic performance2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 43, s. 21760-21771Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hybrid (organic-inorganic) lead trihalide perovskites have attracted much attention in recent years due to their exceptionally promising potential for application in solar cells. Here a controlled one-step method is presented where PbCl2 is combined with three equivalents methylammonium halide (MAX, with X = land/or Br) in polar solvents to form MAPb(I-xBr(x))(3) perovskite films upon annealing in air at 145 degrees C. The procedure allows for a linear increment of the semiconductor bandgap from 1.60 eV to 2.33 eV by increasing the Br content. A transition from a tetragonal to a cubic structure is found when the Br fraction is larger than 0.3. X-ray photoelectron spectroscopy investigations shows that the increase of Br content is accompanied by a shift of the valence band edge to lower energy. Simultaneously, the conduction band moves to higher energy, but this shift is less pronounced. Time-resolved single-photon counting experiments of the perovskite materials on mesoporous TiO2 show faster decay kinetics for Br containing perovskites, indicative of improved electron injection into TiO2. Interestingly, kinetics of MAPb(12.7)Br(0.30)Cl(y) on TiO2 scaffold became faster after prolonged excitation during the measurement. In solar cell devices, MAPb(12.7)Br(0.30)), yielded best performance, giving more than 14% power conversion efficiency when used in combination with an n-type contact consisting of fluorine-doped tinoxide glass coated with dense TiO2 and a mesoporous Al2O3 scaffold, and a p-type contact, spiro-MeOTAD/Ag.

  • 32.
    Pazoki, Meysam
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Röckert, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Wolf, Matthew J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Imani, Roghayeh
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edvinsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Kullgren, Jolla
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Electronic structure of organic–inorganic lanthanide iodide perovskite solar cell materials2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, s. 23131-23138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The emergence of highly efficient lead halide perovskite solar cell materials makes the exploration and engineering of new lead free compounds very interesting both from a fundamental perspective as well as for potential use as new materials in solar cell devices. Herein we present the electronic structure of several lanthanide (La) based materials in the metalorganic halide perovskite family not explored before. Our estimated bandgaps for the lanthanide (Eu, Dy, Tm, Yb) perovskite compounds are in the range of 2.0–3.2 eV showing the possibility for implementation as photo-absorbers in tandem solar cell configurations or charge separating materials. We have estimated the typical effective masses of the electrons and holes for MALaI3 (La= Eu, Dy, Tm, Yb) to be in the range of 0.3–0.5 and 0.97–4.0 units of the free electron mass, respectively. We have shown that the localized f-electrons within our DFT+U approach, make the dominant electronic contribution to the states at the top of the valence band and thus have a strong impact on the photo-physical properties of the lanthanide perovskites. Therefore, the main valence to conduction band electronic transition for MAEuI3 is based on inner shell f-electron localized states within a periodic framework of perovskite crystal by which the optical absorption onset would be rather inert with respect to quantum confinement effects. The very similar crystal structure and lattice constant of the lanthanide perovskites to the widely studied CH3NH3PbI3 perovskite, are prominent advantages for implementation of these compounds in tandem or charge selective contacts in PV applications together with lead iodide perovskite devices

  • 33.
    Phuyal, Dibya
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Jain, Sagar Motilal
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Swansea Univ, Coll Engn, SPECIFIC, Bay Campus,Fabian Way, Swansea SA1 8EN, W Glam, Wales.
    Philippe, Bertrand
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Johansson, Malin B
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Pazoki, Meysam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Kullgren, Jolla
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Kvashnina, Kristina O.
    ESRF, Rossendorf Beamline, CS40220, F-38043 Grenoble 9, France;HZDR, Inst Resource Ecol, POB 510119, D-01314 Dresden, Germany.
    Klintenberg, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Johansson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Butorin, Sergei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Karis, Olof
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    The electronic structure and band interface of cesium bismuth iodide on a titania heterostructure using hard X-ray spectroscopy2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 20, s. 9498-9505Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bismuth halide compounds as a non-toxic alternative are increasingly investigated because of their potential in optoelectronic devices and their rich structural chemistry. Hard X-ray spectroscopy was applied to the ternary bismuth halide Cs3Bi2I9 and its related precursors BiI3 and CsI to understand its electronic structure at an atomic level. We specifically investigated the core levels and valence band using X-ray photoemission spectroscopy (PES), high-resolution X-ray absorption (HERFD-XAS), and resonant inelastic X-ray scattering (RIXS) to get insight into the chemistry and the band edge properties of the two bismuth compounds. Using these element specific X-ray techniques, our experimental electronic structures show that the primary differences between the two bismuth samples are the position of the iodine states in the valence and conduction bands and the degree of hybridization with bismuth lone pair (6s(2)) states. The crystal structure of the two layered quasi-perovskite compounds plays a minor role in modifying the overall electronic structure, with variations in bismuth lone pair states and iodine band edge states. Density Functional Theory (DFT) calculations are used to compare with experimental data. The results demonstrate the effectiveness of hard X-ray spectroscopies to identify element specific bulk electronic structures and their use in optoelectronic devices.

  • 34.
    Safdari, Majid
    et al.
    KTH Royal Inst Technol, Dept Chem, Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Phuyal, Dibya
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Philippe, Bertrand
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Svensson, Per H.
    KTH Royal Inst Technol, Dept Chem, Appl Phys Chem, SE-10044 Stockholm, Sweden.;SP Proc Dev, Sodertalje, Sweden..
    Butorin, Sergei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Kvashnina, Kristina O.
    ESRF European Synchrotron, CS40220, F-38043 Grenoble 9, France.;Helmholtz Zentrum Dresden Rossendorf, Inst Resource Ecol, D-01314 Dresden, Germany..
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Kloo, Lars
    KTH Royal Inst Technol, Dept Chem, Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Gardner, James M.
    KTH Royal Inst Technol, Dept Chem, Appl Phys Chem, SE-10044 Stockholm, Sweden..
    Impact of synthetic routes on the structural and physical properties of butyl-1,4-diammonium lead iodide semiconductors2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 23, s. 11730-11738Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the significant role of synthetic routes and the importance of solvents in the synthesis of organic-inorganic lead iodide materials. Through one route, the intercalation of dimethylformamide in the crystal structure was observed leading to a one-dimensional (1D) [NH3(CH2)(4)NH3]Pb2I6 structure of the product. This product was compared with the two-dimensional (2D) [NH3(CH2)(4)NH3]PbI4 recovered from aqueous solvent based synthesis with the same precursors. UV-visible absorption spectroscopy showed a red-shift of 0.1 eV for the band gap of the 1D network in relation to the 2D system. This shift primarily originates from a shift in the valence band edge as determined from photoelectron-and X-ray spectroscopy results. These findings also suggest the iodide 5p orbital as the principal component in the density of states in the valence band edge. Single crystal data show a change in the local coordination around iodide, while in both materials, lead atoms are surrounded by iodide atoms in octahedral units. The conductivity of the one-dimensional material ([NH3(CH2)(4)NH3]Pb2I6) was 50% of the two-d(i)mensional material ([NH3(CH2)(4)NH3]PbI4). The fabricated solar cells reflect these changes in the chemical and electronic structure of both materials, although the total light conversion efficiencies of solar cells based on both products were similar.

  • 35.
    Stefanov, Bozhidar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Gunnar, Niklasson
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Österlund, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Quantitative relation between photocatalytic activity and degree of〈001〉orientation for anatase TiO2 thin films2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 33, s. 17369-17375Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate a quantitative relation between exposed crystal surfaces and photocatalytic activity of nanocrystalline anatase TiO2. Thin films with controlled amount of 〈001〉 preferential orientation were prepared by reactive DC magnetron sputtering in Ar/O2 atmosphere with the partial O2 pressure as control parameter. The samples were characterized with X-ray diffraction, transmission electron microscopy and atomic force microscopy, from which the degree of preferential 〈001〉 orientation and exposed facets were determined by an extension of the March–Dollase model. Photocatalytic degradation of methylene blue dye shows that the photocatalytic reaction rate increases approximately with the square of the fraction of 〈001〉 oriented surfaces, with about eight times higher rate on the {001} surfaces, than on {101}, thus quantifying the effect of crystal facet abundancy on the photocatalytic activity of anatase TiO2.

  • 36.
    Storm, Mie Møller
    et al.
    Technical University of Denmark.
    Johnsen, Rune E
    Technical University of Denmark.
    Younesi, Reza
    Technical University of Denmark.
    Norby, Poul
    Technical University of Denmark.
    Capillary based Li-air batteries for in situ synchrotron X-ray powder diffraction studies2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, s. 3113-3119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For Li-air batteries to reach their full potential as energy storage system, a complete understanding of the conditions and reactions in the battery during operation is needed. To follow the reactions in situ a capillary-based Li-O2 battery has been developed for synchrotron-based in situ X-ray powder diffraction (XRPD). In this article, we present the results for the analysis of 1st and 2nd deep discharge and charge for a cathode being cycled between 2 and 4.6 V. The crystalline precipitation of Li2O2 only is observed in the capillary battery. However, there are indications of side reactions. The Li2O2 diffraction peaks grow with the same rate during charge and the development of the full width at half maximum (FWHM) is hkl dependent. The difference in the FWHM of the 100 and the 102 reflections indicate anisotropic morphology of the Li2O2 crystallites or defects along the c-axis. The effect of constant exposure of X-ray radiation to the electrolyte and cathode during charge of the battery was also investigated. X-ray exposure during charge leads to changes in the development of the intensity and the FWHM of the Li2O2 diffraction peaks. The X-ray diffraction results are supported by ex situ X-ray photoelectron spectroscopy (XPS) of discharged cathodes to illuminate non-crystalline deposited materials.

  • 37.
    Sun, Bing
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Xu, Chao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Mindemark, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    At the polymer electrolyte interfaces: the role of the polymer host in interphase layer formation in Li-batteries2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 26, s. 13994-14000Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, X-ray photoelectron spectroscopy was applied for compositional analysis of the interphase layers formed in graphite and LiFePO4 Li-battery half cells containing solid polymer electrolytes (SPEs) consisting of poly(trimethylene carbonate) (PTMC) and LiTFSI salt. Decomposition of PTMC was observed at the anode/SPE interface, indicating different reaction products than those associated with the more conventional host material poly(ethylene oxide). Degradation mechanisms of the PTMC host material at low potentials are proposed. Compared to the LiFePO4/PEO interface, the absence of LiOH - a result of water contamination - was generally seen when using hydrophobic PTMC as the polymer host. A clear correlation of moisture content with the constitution of interphase layers in Li polymer batteries could thus be concluded. At the SPE/LiFePO4 interface, good stability was seen regardless of the polymer host materials.

  • 38.
    Svanström, Sebastian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Jacobsson, Jesper
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Sloboda, Tamara
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, Stockholm, Sweden.
    Giangrisostomi, Erika
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Berlin, Germany.
    Ovsyannikov, Ruslan
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Berlin, Germany.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Cappel, Ute
    KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, Stockholm, Swede.
    Effect of halide ratio and Cs+ addition on the photochemical stability of lead halide perovskites2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 44, s. 22134-22144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lead halide perovskite solar cells with multi-cation/mixed halide materials now give power conversion efficiencies of more than 20%. The stability of these mixed materials has been significantly improved through the addition of Cs+ compared to the original methylammonium lead iodide. However, it remains one of the most significant challenges for commercialisation. In this study, we use photoelectron spectroscopy (PES) in combination with visible laser illumination to study the photo-stability of perovskite films with different compositions. These include Br : I ratios of 50 : 50 and 17 : 83 and compositions with and without Cs+. For the samples without Cs and the 50 : 50 samples, we found that the surface was enriched in Br and depleted in I during illumination and that some of the perovskite decomposed into Pb0, organic halide salts, and iodine. After illumination, both of these reactions were partially reversible. Furthermore, the surfaces of the films were enriched in organic halide salts indicating that the cations were not degraded into volatile products. With the addition of Cs+ to the samples, photo-induced changes were significantly suppressed for a 50 : 50 bromide to iodide ratio and completely suppressed for perovskites with a 17 : 83 ratio at light intensities exceeding 1 sun equivalent.

  • 39.
    Sveinbjörnsson, Kári
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Aitola, Kerttu
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Zhang, Jinbao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Johansson, Malin B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Zhang, Xiaoliang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Correa-Baena, Juan-Pablo
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, EPFL SB ISIC LSPM, CH G1 523,Chemin Alamb,Stn 6, CH-1015 Lausanne, Switzerland..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, EPFL SB ISIC LSPM, CH G1 523,Chemin Alamb,Stn 6, CH-1015 Lausanne, Switzerland..
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Uppsala Univ, Dept Chem, Angstrom Lab, Phys Chem, Box 523, S-75120 Uppsala, Sweden..
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Ambient air-processed mixed-ion perovskites for high-efficiency solar cells2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 42, s. 16536-16545Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mixed-ion (FAPbI(3))(1-x)(MAPbBr(3))(x) perovskite solar cells have achieved power conversion efficiencies surpassing 20%. However, in order to obtain these high efficiencies the preparation is performed in a controlled inert atmosphere. Here, we report a procedure for manufacturing highly efficient solar cells with a mixed-ion perovskite in ambient atmosphere. By including a heating step at moderate temperatures of the mesoporous titanium dioxide substrates, and spin-coating the perovskite solution on the warm substrates in ambient air, a red intermediate phase is obtained. Annealing the red phase at 100 degrees C results in a uniform and crystalline perovskite film, whose thickness is dependent on the substrate temperature prior to spin-coating. The temperature was optimized between 20 and 100 degrees C and it was observed that 50 degrees C substrate temperature yielded the best solar cell performances. The average efficiency of the best device was 17.6%, accounting for current-voltage (I-V) measurement hysteresis, with 18.8% performance in the backward scan direction and 16.4% in the forward scan direction. Our results show that it is possible to manufacture high-efficiency mixed-ion perovskite solar cells under ambient conditions, which is relevant for large-scale and low-cost device manufacturing processing.

  • 40.
    Wang, Baoyuan
    et al.
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China.;Royal Inst Technol, Dept Energy Technol, SE-10044 Stockholm, Sweden..
    Wang, Yi
    Max Planck Inst Solid State Res MPI FKF, Stuttgart Ctr Electron Microscopy StEM, Heisenbergstr 1, D-70569 Stuttgart, Germany..
    Fan, Liangdong
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China.;Shenzhen Univ, Coll Chem & Environm Engn, Shenzhen 518060, Guangdong, Peoples R China..
    Cai, Yixiao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Xia, Chen
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China.;Royal Inst Technol, Dept Energy Technol, SE-10044 Stockholm, Sweden..
    Liu, Yanyan
    Royal Inst Technol, Dept Energy Technol, SE-10044 Stockholm, Sweden..
    Raza, Rizwan
    COMSATS Inst Informat Technol, Dept Phys, Islamabad, Pakistan..
    van Aken, Peter A.
    Max Planck Inst Solid State Res MPI FKF, Stuttgart Ctr Electron Microscopy StEM, Heisenbergstr 1, D-70569 Stuttgart, Germany..
    Wang, Hao
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Zhu, Bin
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China.;Royal Inst Technol, Dept Energy Technol, SE-10044 Stockholm, Sweden..
    Preparation and characterization of Sm and Ca co-doped ceria-La0.6Sr0.4Co0.2Fe0.8O3-delta semiconductor-ionic composites for electrolyte-layer-free fuel cells2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 40, s. 15426-15436Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of Sm and Ca co-doped ceria, i.e. Ca0.04Ce0.96-xSmxO2-delta (x = 0, 0.09, 0.16, and 0.24) (SCDC), were synthesized by a co-precipitation method. Detailed morphology, composition, crystal structure and electrochemical properties of the prepared materials were characterized. The results revealed that Sm and Ca co-doping could enhance the ionic conductivity in comparison with that of single Ca-doped samples. The composition as Ca0.04Ce0.80Sm0.16O2-delta exhibited a highest ionic conductivity of 0.039 S cm(-1) at 600 degrees C in comparison with the rest of the series, and the optimal ionic conductivity can be interpreted by the coupling effect of oxygen vacancies and mismatch between the dopant ionic radius and critical radius. Composite formation between the semiconductor La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) and the as-prepared SCDC contributed to a remarkable improvement in the ionic conductivity, an unexpectedly high ionic conductivity of 0.188 S cm(-1) was obtained for LSCF-SCDC composites at 600 degrees C, which was four times higher than that of pure SCDC. Using transmission electron microscopy and spectroscopy approaches, we detected an enrichment of oxygen in the LSCF-SCDC interface region and a depletion of oxygen vacancies in LSCF-SCDC and LSCF-LSCF grain boundaries was significantly mitigated, which resulted in the enhancement of ionic conductivity of semiconductor-ionic LSCF-SCDC composites. The electrolyte-layer-free fuel cell (EFFC) fabricated from the LSCF-SCDC semiconductor-ionic membrane demonstrated excellent performances, e.g. 814 mW cm(-2) at 550 degrees C for using the LSCF-Ca0.04Ce0.80Sm0.16O2-delta (SCDC2).

  • 41.
    Wang, Zhaohui
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Tammela, Petter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Huo, Jinxing
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Zhang, Peng
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Solution-processed poly(3,4-ethylenedioxythiophene) nanocomposite paper electrodes for high-capacitance flexible supercapacitors2016Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, nr 5, s. 1714-1722Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although the development of nanostructured poly(3,4-ethylenedioxythiophene) (PEDOT) with large capacitance and high mechanical flexibility is crucial for the realization of high-performance supercapacitors, such electrodes are generally very challenging to manufacture rapidly and inexpensively. Herein, a straightforward, fast and versatile approach for the fabrication of mechanically robust, highly conductive and flexible nanostructured PEDOT paper is described. The composite material, which can be made within 30 minutes using solution based reactions, exhibits a large surface area (137 m2 g-1) and low sheet resistance (1.4 [capital Omega] [square]-1) as well as high active mass loading (7.3 mg cm-2). Symmetric PEDOT paper-based supercapacitors are shown to provide high specific electrode capacitances (i.e. 90 F g-1, 920 mF cm-2, and 54 F cm-3) and excellent cycling stability (93% capacity retention after 15 000 cycles at 30 mA cm-2) in 1.0 M H2SO4. The electrochemical performance of the supercapacitors was also maintained at different bending angles demonstrating the flexibility of the devices. Given the widespread interest in PEDOT and its broad applicability, the present straightforward procedure for the fabrication of nanostructured PEDOT holds great promise for the realization of different flexible energy storage devices.

  • 42.
    Wang, Zhaohui
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Tammela, Petter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Zhang, Peng
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    High areal and volumetric capacity sustainable all-polymer paper-based supercapacitors2014Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, nr 39, s. 16761-16769Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    All-polymer paper-based electrodes with a thickness up to hundreds of micrometers (e.g. 290 mu m), large active mass loadings (>20 mg cm(-2)) and relatively high densities (1.23 g cm(-3)) can be straightforwardly obtained from pristine low-cost polypyrrole-cellulose composites by decreasing the porosity of the material via space engineering. By straightforward compression of the composites, compact capacitive storage devices with improved space utilization are obtained without significantly compromising the electrochemical performance of the devices. This indicates that the compression unlike other methods previously used to vary the porosity of these composites does not affect the distribution of the mesopores which mainly determines the electrochemical performance of the material. When used to manufacture green supercapacitors comprising entirely of environmentally friendly materials, the freestanding and binder-free porous yet dense electrodes yield an areal capacitance of 5.66 F cm(-2), a device volumetric energy density of 3.7 W h L-1 (based on the volume of the entire device) and the largest volumetric electrode capacitance of 236 F cm(-3) so far reported for conducting polymer-based electrodes. The presented results for symmetric supercapacitors containing aqueous electrolytes represent significant progress in the development of inexpensive and environmentally friendly high-performance paper-based energy storage devices.

  • 43.
    Wang, Zhaohui
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Xu, Chao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tammela, Petter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Huo, Jinxing
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad mekanik.
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Flexible freestanding Cladophora nanocellulose paper based Si anodes for lithium-ion batteries2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 27, s. 14109-14115Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Freestanding, lightweight and flexible Si paper anodes are prepared via a straightforward paper-making process using Cladophora nano-cellulose, silicon nanoparticles and carbon nanotubes as the building blocks. The uniform Si particle distribution and strong adhesion of the Si nanoparticles to the porous, conductive and flexible nanocellulose/carbon nanotube 3D matrix yield specific capacities of up to 800 mA h g(-1) (based on the weight of whole electrode) and very good cycling performances.

  • 44.
    Watcharatharapong, Teeraphat
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Chakraborty, Sudip
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Indian Inst Technol Indore, Discipline Phys, Indore 453552, Madhya Pradesh, India.
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden.
    Mapping Sodium Intercalation Mechanism, Electrochemical Properties and Structural Evolution in Non-stoichiometric Alluaudite Na2+2δFe2-δ(SO4)3 Cathode Materials2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, s. 17446-17455Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the scientific advancement of future cathode materials, alluaudite sodium iron sulfate Na2+2δFe2−δ(SO4)3 (NxFyS) has emerged as one of the most promising candidates for sustainable sodium-ion batteries due to its high Fe2+/3+ redox potential (3.8 V vs.Na/Na+), low cost, and high rate capability. Usually, this material occurs in a non-stoichiometric form with partial Na+ substitutions on Fe sites, where δ is close to 0.25 (N2.5F1.75S) depending on the synthesis conditions. While many contemporary works have primarily been directed to study this non-stoichiometric compound, our previous theoretical prediction unveiled the possibility to synthesize stoichiometric alluaudite (N2F2S), which is expected to deliver higher specific capacity (∼120 mA h g−1) as compared to the non-stoichiometric derivatives. This provokes curiosity toward the non-stoichiometric effect on the electrochemical activities and sodium intercalation mechanism in alluaudite materials. In this work, we therefore perform rigorous first-principles calculations to study the structural evolution, electrochemical behavior, and voltage profile of NxFyS with y = 2, 1.75, and 1.5. We reveal the likelihood of two phase transitions after half desodiation process, whereas the probability is reduced with a higher degree of non-stoichiometry, suggesting improvement in the structural reversibility for N2.5F1.75S and N3F1.5S. The prediction of the voltage profiles shows the benefit of non-stoichiometry in enhancing the specific capacity and identifies the structural rearrangement of Fe2O10 dimers as the hidden reason behind the irreversible sharp peak experimentally observed in differential galvanostatic profiles.

  • 45.
    Watcharatharapong, Teeraphat
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    T-Thienprasert, Jiraroj
    Kasetsart Univ, Fac Sci, Dept Phys, Bangkok 10900, Thailand..
    Barpanda, Prabeer
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, Bangalore 560012, Karnataka, India..
    Ahuja, Rajeev
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Chakraborty, Sudip
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Mechanistic study of Na-ion diffusion and small polaron formation in Kröhnkite Na2Fe(SO4)2·2H2O based cathode materials2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 41, s. 21726-21739Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Kröhnkite-type Na2Fe(SO4)2·2H2O mineral is a sustainable and promising polyanionic cathode that has been experimentally found to offer a high redox potential (3.25 V vs. Na/Na+) along with fast-ion diffusion and high reversibility. Owing to the structural complexity, Na+ diffusion was assumed to occur along a convoluted channel along the b-axis. However, theoretical work related to this material still appears missing to support that statement. In this work, DFT+U calculations have been performed with the primary aim to unveil the Na+ diffusion mechanism in this material. The electronic structure and charge transfer are also envisaged to reveal evidence of Fe2+/3+ redox reaction and a vital role of structural H2O. Based on formation energies of this material with varied Na concentration, a calculated voltage profile is determined to show two voltage plateaus at 4.81 and 3.51 V, corresponding to experimental results. Nudged elastic band calculation reveals that Na+ diffusion is primarily occuring in the [01] direction with a moderate ionic mobility due to the structural distortion induced during migration, suggesting the possibility of defect-assisted diffusion. Intriguingly, the formation of small hole polarons is first observed, and could play a key role in the electronic conduction of this material.

  • 46.
    Wijaya, Olivia
    et al.
    TUM CREATE, Singapore 138602, Singapore..
    Hartmann, Pascal
    Univ Giessen, Inst Phys Chem, D-35392 Giessen, Germany..
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Markovits, Iulius I. E.
    Nanyang Technol Univ, Energy Res Inst, Singapore 637141, Singapore..
    Rinaldi, Ali
    TUM CREATE, Singapore 138602, Singapore..
    Janek, Jurgen
    Univ Giessen, Inst Phys Chem, D-35392 Giessen, Germany..
    Yazami, Rachid
    Nanyang Technol Univ, Energy Res Inst, Singapore 637141, Singapore..
    A gamma fluorinated ether as an additive for enhanced oxygen activity in Li-O-2 batteries2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 37, s. 19061-19067Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Perfluorocarbons (PFCs) are known for their high O-2 solubility and have been investigated as additives in Li-O-2 cells to enhance the cathode performance. However, the immiscibility of PFCs with organic solvents remains the main issue to be addressed as it hinders PFC practical application in Li-O-2 cells. Furthermore, the effect of PFC additives on the O-2 mass transport properties in the catholyte and their stability has not been thoroughly investigated. In this study, we investigated the properties of 1,1,1,2,2,3,3,4,4-nonafluoro-6-propoxyhexane (TE4), a gamma fluorinated ether, and found it to be miscible with tetraglyme (TEGDME), a solvent commonly used in Li-O-2 cells. The results show that with the TE4 additive up to 4 times higher O-2 solubility and up to 2 times higher O-2 diffusibility can be achieved. With 20 vol% TE4 addition, the discharge capacity increased about 10 times at a high discharge rate of 400 mA g(C)(-1), corresponding to about 0.4 mA cm(-2). The chemical stability of TE4 after Li-O-2 cell discharge is investigated using H-1 and F-19 NMR, and the TE4 signal is retained after discharge. FTIR and XPS measurements indicate the presence of Li2O2 as a discharged product, together with side products from the parasitic reactions of LiTFSI salt and TEGDME.

  • 47.
    Xu, Chao
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material. Nanjing Tech Univ.
    Kong, Xueying
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material. Nanjing Tech Univ.
    Zhou, Shengyang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Zheng, Bing
    Huo, Fengwei
    Strömme, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Nanoteknologi och funktionella material.
    Interweaving metal-€“organic framework-templated Co-€“Ni layered double hydroxide nanocages with nanocellulose and carbon nanotubes to make flexible and foldable electrodes for energy storage devices2018Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, nr 47, s. 24050-24057Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metal–organic frameworks (MOFs) and nanocellulose represent emerging and traditional porous materials{,} respectively. The combination of these two materials in specific ways could generate novel nanomaterials with integrated advantages and versatile functionalities. This study outlines the development of hierarchical porous and conductive nanosheets based on zeolitic imidazolate framework-67 (ZIF-67{,} a Co-based MOF)-templated Co–Ni layered double hydroxide (LDH) nanocages{,} Cladophora cellulose (CC) nanofibers{,} and multi-walled carbon nanotubes (CNTs). The LDH–CC–CNT nanosheets can be used as flexible and foldable electrodes for energy storage devices (ESDs). The electrodes are associated with a high areal capacitance of up to 1979 mF cm−2 at a potential scan rate of 1 mV s−1. A flexible{,} foldable{,} and hybrid ESD is assembled from LDH–CC–CNT and CC–CNT electrodes with a PVA/KOH gel. The entire device has an areal capacitance of 168 mF cm−2 and an energy density of 0.6 mW h cm−3 (60 ÎŒW h cm−2){,} at a power density of 8.0 mW cm−3 (0.8 mW cm−2). These promising results demonstrate the potential of using MOFs and sustainable cellulose in flexible{,} foldable elec

  • 48.
    Zhang, Keliang
    et al.
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    Zhang, Xudong
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    He, Wen
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    Xu, Wangning
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    Xu, Guogang
    Shandong Univ Sci & Technol, Coll Mat Sci & Engn, Qingdao 266590, Shandong, Peoples R China.
    Yi, Xinli
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    Yang, Xuena
    Qilu Univ Technol, Shandong Acad Sci, Coll Mat Sci & Engn, Jinan 250353, Shandong, Peoples R China.
    Zhu, Jie-Fang
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Rational design and kinetics study of flexible sodium-ion full batteries based on binder-free composite film electrodes2019Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 16, s. 9890-9902Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A high-performance flexible sodium-ion full battery (FSIFB) is developed by using binder-free composite film (BFCF) electrodes without using conductive carbon and current collectors. Hard carbon fibers decorated with different electrochemical active materials are used as the supporting framework and 3D conductive network of FSIFBs for the first time. Different pre-sodiated anodes and the electrolyte additives are designed for well-matched FSIFBs. Using a porous Na3V2(PO4)(3) coated hard carbon fiber film with a mass loading of 2.34 mg cm(-2) as the cathode and a pre-sodiated graphene/SiC/hard carbon fiber film with a mass loading of 1.50 mg cm(-2) as the anode, an optimized FSIFB is designed. It delivers high output voltage (3.34 V), high energy density (234.1 W h kg(-1) at a high-current rate of 0.5 A g(-1)), ultralong cyclability (over 2905 cycles at 0.5 A g(-1) and 1000 cycles at 5 A g(-1)), and high coulombic efficiency (approaching 100%), which surpasses those of all FSIFBs reported so far. Furthermore, this FSIFB still maintains good electrochemical attributes even at serious bending states in water. The models of the solid electrolyte interphase behavior on the surface of electrodes in the FSIFB are studied by using EIS, and a reaction mechanism and an equivalent electrical circuit are proposed. We also provide the videos of the preparation process for a pouch-type FSIFB to demonstrate its simple operability and potential applications.

  • 49.
    Zhang, Xiaoliang
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Reduction of charge recombination in PbS colloidal quantum dot solar cells at the quantum dot/ZnO interface by inserting a MgZnO buffer layer2017Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, nr 1, s. 303-310Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Interfacial charge recombination occurring at the interface between a colloidal quantum dot (CQD) solid and the electron collecting layer (ECL) in CQD solar cells significantly affects the charge carrier collection, therefore limiting the device photovoltaic performance. In this work CQD solar cells with an improved performance are reported by employing MgZnO as a buffer layer (BL) with tunable electronic energy levels in the solar cells to reduce interfacial charge recombination and hence improve the solar cell photovoltaic performance. The effect of the BL on the solar cell performance is experimentally investigated and compared to theoretical calculations. Incorporation of a BL with favorable electronic energy levels forming a suitable band alignment with the CQD layer in solar cells diminishes the interfacial charge recombination and an increased photovoltage can be obtained. A CQD solar cell with a BL shows a power conversion efficiency of up to 9.3%, compared to that of 8.2% for a solar cell without any BLs. The unsealed solar cells are also rather stable under ambient conditions both in the dark and under continuous illumination. This work suggests that a MgZnO BL with energy level tunability provides a potential strategy to improve the interfacial properties of CQD photovoltaic devices.

  • 50.
    Zhang, Xiaoliang
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Justo, Yolanda
    Maes, Jorick
    Walravens, Willem
    Zhang, Jindan
    Liu, Jianhua
    Hens, Zeger
    Johansson, Erik M. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Slow recombination in quantum dot solid solar cellusing p–i–n architecture with organic p-type holetransport material2015Inngår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, nr 41, s. 20579-20585Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interfaces between different materials in the heterojunction colloidal quantum dot (QD) solar cell playan important role for charge carrier separation, recombination and collection. Here, an organic–inorganichybrid p–i–n architecture for the heterojunction PbS QD solid solar cell is constructed to increase thecharge extraction and reduce charge recombination. Heavily doped poly(3-hexylthiophene-2,5-diyl)(P3HT) is applied as hole transport interlayer between the QD film and metal contact electrode. Theresults show that the P3HT interlayer diminishes the charge carrier recombination at the QD film/metalcontact electrode interface leading to increased open-circuit voltage and increased electron life time.Furthermore, after incorporation of P3HT interlayer an additional p–i heterojunction might form atP3HT/QD film interface resulting in increased depletion region, which promotes charge carrierextraction under working conditions. Two other organic p-type interlayers are also investigated,however, the results indicate that a barrier for charge extraction is formed for these devices, which isexplained by the difference in energy levels. The solar cell with the P3HT interlayer exhibits a powerconversion efficiency of 5.1% at 1 sun of illumination and ambient atmosphere, which is 20% highercompared to the solar cell without any hole transport interlayer.

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