uu.seUppsala University Publications
Change search
Refine search result
1 - 42 of 42
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Agervald, Åsa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry.
    Camsund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Stensjö, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Lindblad, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    CRISPR in the extended hyp-operon of the cyanobacterium Nostoc sp. strain PCC 7120, characteristics and putative function(s)2012In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, no 10, p. 8828-8833Article in journal (Refereed)
    Abstract [en]

    The presence of small RNAs (sRNA) and their functions in transcriptional regulation has lately turned into a hot topic. Since cyanobacteria often face changes in the surrounding environment, they need to have a well working system for stress response. Quick adaption is necessary, and an RNA-based regulatory system is thus useful. One example of these sRNAs is CRISPRs. In this work we report the existence of a CRISPR within the hyp-operon (hyp genes encode proteins responsible for the maturation of hydrogenases) of the filamentous cyanobacterium Nostoc sp. strain PCC 7120. We present data concerning its characteristics and putative function(s) and raise the question concerning the importance of this CRISPR array and other CRISPR systems in general. In addition, we discuss the use of the CRISPR system as a potential bacterial genetic defence mechanism to achieve robust, cyanobacterial cultures in large scale, commercial production units.

  • 2. Almeida, Cristiane G.
    et al.
    Araujo, Rafael B.
    Yoshimura, Rafael G.
    Mascarenhas, Artur J. S.
    da Silva, Antonio Ferreira
    Araujo, Carlos Moyses
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Silva, Luciana A.
    Photocatalytic hydrogen production with visible light over Mo and Cr-doped BiNb(Ta)O-42014In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, no 3, p. 1220-1227Article in journal (Refereed)
    Abstract [en]

    In the present work, we prepared pure and Cr(III) and Mo(V)-doped BiNbO4 and BiTaO4 by the citrate method. Pure BiNbO4 and BiTaO4 were obtained in triclinic phase at 600 degrees C and 800 degrees C, respectively. The metal doping influenced strongly the crystal structure as well as the photocatalytic activity of the oxides. The XRD data could prove that the Mo(V) doping induces the orthorhombic phase, while the Cr(III) doping favors the triclinic phase for both oxides. Metal doping also modified the photosensitivity of the oxides, extending the absorption toward the visible light region. The photocatalytic activity in water splitting under visible light irradiation was evaluated by monitoring the H-2, CO2 and CO evolution. The results showed that Cr(III)-doped BiTaO4 and BiNbO4, in general, are more selective for hydrogen production, while Mo(V)-doped materials are more selective for CO2 generation. Comparing the photocatalytic activity of BiTaO4 and BiNbO4, the former shows higher activity for hydrogen production as well as for CO2 generation, specially when the concentration was 2% in Cr(III) and Mo(V), respectively. Those results are in agreement with the computational study to access the effect of doping on the electronic structure. For Mo(V)-doped materials a negligible change of conduction band minimum potential was found, indicating that there might be no improvement on the reduction power of the material following the substitutional doping. In Cr(III)-doped BiNbO4 there is a slight shift of the CBM potential increasing a little bit the reduction power. However, the effect is much stronger in the Cr(III)-doped BiTaO4.

  • 3. Antal, Taras
    et al.
    Oliveira, Paulo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Lindblad, Peter
    The bidirectional hydrogenase in the cyanobacterium Synechocystis sp. strain PCC 68032006In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 31, no 11, p. 1439-1444Article in journal (Refereed)
  • 4. Baebprasert, Wipawee
    et al.
    Lindblad, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry.
    Incharoensakdi, Aran
    Response of H-2 production and Hox-hydrogenase activity to external factors in the unicellular cyanobacterium Synechocystis sp strain PCC 68032010In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 35, no 13, p. 6611-6616Article in journal (Refereed)
    Abstract [en]

    The effects of external factors on both H-2 production and bidirectional Hox-hydrogenase activity were examined in the non-N-2-fixing cyanobacterium Synechocystis PCC 6803. Exogenous glucose and increased osmolality both enhanced H-2 production with optimal production observed at 0.4% and 20 mosmol kg(-1), respectively. Anaerobic condition for 24 h induced significant higher H(2)ase activity with cells in BC11(0) showing highest activities. Increasing the pH resulted in an increased Hox-hydrogenase activity with an optimum at pH 7.5. The Hox-hydrogenase activity gradually increased with increasing temperature from 30 degrees C to 60 degrees C with the highest activity observed at 70 degrees C. A low concentration at 100 mu M of either DTT or beta-mercaptoethanol resulted in a minor stimulation of H-2 production. beta-Mercaptoethanol added to nitrogen- and sulfur-deprived cells stimulated H-2 production significantly. The highest Hox-hydrogenase activity was observed in cells in BG11(0)-S-deprived condition and 750 mu M beta-mercaptoethanol measured at a temperature of 70 degrees C; 14.32 mu mol H-2 mg chl alpha(-1) min(-1).

  • 5.
    Banerjee, Paramita
    et al.
    Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata 700032, India..
    Pathak, Biswarup
    Indian Inst Technol, Discipline Chem, Indore 452020, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Das, G. P.
    Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata 700032, India..
    First principles design of Li functionalized hydrogenated h-BN nanosheet for hydrogen storage2016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 32, p. 14437-14446Article in journal (Refereed)
    Abstract [en]

    Employing first principles density functional theory (DFT) based approach, the structure, stability and hydrogen storage efficiency of a hydrogenated hexagonal boron nitride sheet (BHNH chair conformer) functionalized by the lightest alkali metal atom Li has been explored here in details. Substituting one hydrogen atom from both B and N sides of BHNH sheet by a Li atom, we have found that Li becomes cationic and acts as a binding site to adsorb hydrogen molecules. The stability of this Li-substituted BHNH sheet has been indicated via Ab-initio Molecular Dynamics (AIMD) simulation upto 400 K. The binding energy (similar to 0.18-0.3 eV/H-2 molecule) and gravimetric density (similar to 6 wt %) (upto similar to 200 K) of the hydrogen molecules fall in the required window for practical hydrogen storage. AIMD simulation indicates complete dehydrogenation from this system occurs at similar to 400 K, thereby predicting the suitability of this system from the point of view of efficient hydrogen storage.

  • 6.
    Callini, Elsa
    et al.
    EPFL Valais Wallis Swiss Fed Inst Technol, LMER, Rue Ind 17, CH-1950 Sion, Switzerland.;Swiss Fed Lab Mat Sci & Technol, Empa, Ueberlandstr 129, CH-8600 Dubendorf, Switzerland..
    Aguey-Zinsou, Kondo-Francois
    Univ New S Wales, Sch Chem Engn, MERLin Grp, Sydney, NSW 2052, Australia..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Ramon Ares, Jose
    Univ Autonoma Madrid, Fac Ciencias, Dpto Fis Mat, Grp Mire, E-28049 Madrid, Spain..
    Bals, Sara
    Univ Antwerp, Dept Phys, EMAT, Groenenborgerlaan 171, B-2020 Antwerp, Belgium..
    Biliskov, Nikola
    Rudjer Boskovic Inst, Bijenicka Cesta 54, Zagreb 10000, Croatia..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Charalambopoulou, Georgia
    Natl Ctr Sci Res Demokritos, Athens 15341, Greece..
    Chaudhary, Anna-Lisa
    Helmholtz Zentrum Geesthacht, Inst Mat Res, Dept Nanotechnol, Max Planck Str 1, Geesthacht, Germany..
    Cuevas, Fermin
    UPEC, CNRS, ICMPE, UMR7182, 2-8 Rue Henri Dunant, F-94320 Thiais, France..
    Dam, Bernard
    Delft Univ Technol, Chem Engn, Julianalaan 136, NL-2628 BL Delft, Netherlands..
    de Jongh, Petra
    Univ Utrecht, Debye Inst Nanomat Sci, Inorgan Chem & Catalysis, Univ Weg 99, NL-3584 CG Utrecht, Netherlands..
    Dornheim, Martin
    Helmholtz Zentrum Geesthacht, Inst Mat Res, Dept Nanotechnol, Max Planck Str 1, Geesthacht, Germany..
    Filinchuk, Yaroslav
    Catholic Univ Louvain, Inst Condensed Matter & Nanosci, B-1348 Louvain, Belgium..
    Novakovic, Jasmina Grbovic
    Univ Belgrade, Vinca Inst Nucl Sci, POB 522, Belgrade 1000, Serbia..
    Hirscher, Michael
    Max Planck Inst Intelligent Syst Stuttgart, Heisenbergstr 3, D-70569 Stuttgart, Germany..
    Jensen, Torben R.
    Aarhus Univ, Dept Chem, Ctr Mat Crystallog, Langelandsgade 140, DK-8000 Aarhus C, Denmark.;Aarhus Univ, iNANO, Langelandsgade 140, DK-8000 Aarhus C, Denmark..
    Jensen, Peter Bjerre
    Tech Univ Denmark, Dept Energy Convers & Storage, Fysikvej,Bldg 309, DK-2800 Lyngby, Denmark..
    Novakovic, Nikola
    Univ Belgrade, Vinca Inst Nucl Sci, POB 522, Belgrade 1000, Serbia..
    Lai, Qiwen
    Univ New S Wales, Sch Chem Engn, MERLin Grp, Sydney, NSW 2052, Australia..
    Leardini, Fabrice
    Univ Autonoma Madrid, Fac Ciencias, Dpto Fis Mat, Grp Mire, E-28049 Madrid, Spain..
    Gattia, Daniele Mirabile
    Res Ctr Casaccia, ENEA, Dept Phys Methods & Mat, Via Anguillarese 301, Rome, Italy..
    Pasquini, Luca
    Alma Mater Studiorum Univ Bologna, Dept Phys & Astron, I-40127 Bologna, Italy..
    Steriotis, Theodore
    Natl Ctr Sci Res Demokritos, Athens 15341, Greece..
    Turner, Stuart
    Univ Antwerp, Dept Phys, EMAT, Groenenborgerlaan 171, B-2020 Antwerp, Belgium..
    Vegge, Tejs
    Tech Univ Denmark, Dept Energy Convers & Storage, Fysikvej,Bldg 309, DK-2800 Lyngby, Denmark..
    Zuttel, Andreas
    EPFL Valais Wallis Swiss Fed Inst Technol, LMER, Rue Ind 17, CH-1950 Sion, Switzerland..
    Montone, Amelia
    Res Ctr Casaccia, ENEA, Dept Phys Methods & Mat, Via Anguillarese 301, Rome, Italy..
    Nanostructured materials for solid-state hydrogen storage: A review of the achievement of COST Action MP11032016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 32, p. 14404-14428Article in journal (Refereed)
    Abstract [en]

    In the framework of the European Cooperation in Science and Technology (COST) Action MP1103 Nanostructured Materials for Solid-State Hydrogen Storage were synthesized, characterized and modeled. This Action dealt with the state of the art of energy storage and set up a competitive and coordinated network capable to define new and unexplored ways for Solid State Hydrogen Storage by innovative and interdisciplinary research within the European Research Area. An important number of new compounds have been synthesized: metal hydrides, complex hydrides, metal halide ammines and amidoboranes. Tuning the structure from bulk to thin film, nanoparticles and nanoconfined composites improved the hydrogen sorption properties and opened the perspective to new technological applications. Direct imaging of the hydrogenation reactions and in situ measurements under operando conditions have been carried out in these studies. Computational screening methods allowed the prediction of suitable compounds for hydrogen storage and the modeling of the hydrogen sorption reactions on mono-, bi-, and three-dimensional systems. This manuscript presents a review of the main achievements of this Action.

  • 7. Dasgupta, Chitralekha Nag
    et al.
    Gilbert, J. Jose
    Lindblad, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry.
    Heidorn, Thorsten
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry.
    Borgvang, Stig A.
    Skjanes, Kari
    Das, Debabrata
    Recent trends on the development of photobiological processes and photobioreactors for the improvement of hydrogen production2010In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 35, no 19, p. 10218-10238Article in journal (Refereed)
    Abstract [en]

    Hydrogen production through biological routes is promising because they are environmentally friendly. Hydrogen production through biophotolysis or photofermentation is usually a two stage process. In the first stage CO2 is utilized for biomass production which is followed by hydrogen production in the second stage in anaerobic/sulfur-deprived conditions. In addition, one-stage photobiological hydrogen production process can be achieved using selected cyanobacterial strains. The major challenges confronting the large scale production of biomass/hydrogen are limited not only on the performance of the photobioreactors in which light penetration in dense cultures is a major bottleneck but also on the characteristics of the organisms. Other dependable factors include area/volume (AN) ratio, mode of agitation, temperature and gas exchange. Photobioreactors of different geometries are reported for biohydrogen production: Tubular, Flat plate, Fermentor type etc. Every reactor has its own advantages and disadvantages. Airlift, helical tubular and flat plate reactors are found most suitable with respect to biomass production. These bioreactors may be employed for hydrogen production with necessary modifications to overcome the existing bottlenecks like gas hold up, oxygen toxicity and poor agitation. This review article attempts to focus on existing photobioreactors with respect to biomass generation and hydrogen production and the steps taken to improve its performance through engineering innovation that definitely help in the future design and construction of photobioreactors.

  • 8. Dixit, Mudit
    et al.
    Maark, Tuhina Adit
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Pal, Sourav
    Ab initio and periodic DFT investigation of hydrogen storage on light metal-decorated MOF-52011In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 36, no 17, p. 10816-10827Article in journal (Refereed)
    Abstract [en]

    The effect of light metal (M = Li, Be, Mg, and Al) decoration on the stability of metal organic framework MOF-5 and its hydrogen adsorption is investigated by ab initio and periodic density functional theory (DFT) calculations by employing models of the form BDC:M(2):nH(2) and MOF-5:M(2):nH(2), where BDC stands for the benzenedicarboxylate organic linker and MOF-5 represents the primitive unit cell. The suitability of the periodic DFT method employing the GGA-PBE functional is tested against MP2/6-311 + G* and MP2/cc-pVTZ molecular calculations. A correlation between the charge transfer and interaction energies is revealed. The metal-MOF-5 interactions are analyzed using the frontier molecular orbital approach. Difference charge density plots show that H(2) molecules get polarized due to the charge generated on the metal atom adsorbed over the BDC linker, resulting in electrostatic guest-host interactions. Our solid state results show that amongst the four metal atoms, Mg and Be decoration does not stabilize the MOF-5 to any significant extent. Li and Al decoration strengthened the H(2)-MOE-5 interactions relative to the pure MOF-5 exhibited by the enhanced binding energies. The hydrogen binding energies for the Li- and Al-decorated MOF-5 were found to be sensible for allowing reversible hydrogen storage at ambient temperatures. A high hydrogen uptake of 4.3 wt.% and 3.9 wt.% is also predicted for the Li- and Al-decorated MOF-5, respectively. Copyright (C) 2011, Hydrogen Energy Publications, LLC.

  • 9. Guo, Zhonglu
    et al.
    Sa, Baisheng
    Pathak, Biswarup
    Zhou, Jian
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Sun, Zhimei
    Band gap engineering in huge-gap semiconductor SrZrO3 for visible-light photocatalysis2014In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, no 5, p. 2042-2048Article in journal (Refereed)
    Abstract [en]

    Using SrZrO3 (SZO, the intrinsic band gap being 5.6 eV) as an example, we have investigated the design principles for huge-gap semiconductors with band gap larger than 5 eV for the application of efficient visible-light driven photocatalysts for splitting water into hydrogen. Based on the hybrid density function calculations, the electronic structures of mono-doped and co-doped SZO are investigated to obtain design principles for improving their photocatalytic activity in hydrogen generation. The cationic-anionic co-doping in SZO could reduce the band gap significantly and its electronic band position is excellent for the visible-light photocatalysis. This work reports a new type of candidate material for visible-light driven photocatalysis, i.e., huge-gap semiconductors with band gap larger than 5 eV. Furthermore, based on the present results we have proposed the design principles for band gap engineering that provides general guideline for other huge-gap semiconductors.

  • 10. Hinkley, James T.
    et al.
    O'Brien, Jessica A.
    Fell, Christopher J.
    Lindquist, Sten-Eric
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Prospects for solar only operation of the hybrid sulphur cycle for hydrogen production2011In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 36, no 18, p. 11596-11603Article in journal (Refereed)
    Abstract [en]

    The hybrid sulphur process is one of the most promising thermochemical water splitting cycles for large scale hydrogen production. While the process includes an electrolysis step, the use of sulphur dioxide in the electrolyser significantly reduces the electrical demand compared to conventional alkaline electrolysis. Solar operation of the cycle with zero emissions is possible if the electricity for the electrolyser and the high temperature thermal energy to complete the cycle are provided by solar technologies. This paper explores the possible use of photovoltaics (PV) to supply the electrical demand and examines a number of configurations. Production costs are determined for several scenarios and compared with base cases using conventional technologies. The hybrid sulphur cycle has promise in the medium term as a viable zero carbon production process if PV power is used to supply the electrolyser. However, the viability of this process is dependent on a market for hydrogen and a significant reduction in PV costs to around $1/W(p).

  • 11.
    Hussain, Tanveer
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sarkar, Abir De
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Department of Physics, Central University of Rajasthan,.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Department of Materials and Engineering, Royal Institute of Technology (KTH).
    Functionalization of hydrogenated graphene by polylithiated species for efficient hydrogen storage2014In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, no 6, p. 2560-2566Article in journal (Refereed)
    Abstract [en]

    The hydrogen (H-2) storage capacity of defected graphane (CH) functionalized by polylithiated species CLi3 and CLi4 has been investigated by means of first-principles DFT calculations. The stability and electronic structures of these potential H-2 storage materials have also been studied. The binding of these lithium rich species (CLi3, CLi4) to the CH sheet has been found to be strong enough to avoid clustering. The nature of bonding in C-Li and C-C has been revealed by Bader charge analysis. It has been found that when both sides of CH sheet are functionalized by polylithiated species, a storage capacity of more than 13 wt % can be achieved with adsorption energies of H-2 in the range of 0.25 eV-0.35 eV, which is suitable for an efficient H-2 storage.

  • 12. Ivanou, M. F.
    et al.
    Kiverin, A. D.
    Liberman, Michael A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Flame acceleration and DDT of hydrogen-oxygen gaseous mixtures in channels with no-slip walls2011In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 36, no 13, p. 7714-7727Article in journal (Refereed)
    Abstract [en]

    Hydrogen-oxygen flame acceleration and transition from deflagration to detonation (DDT) in channels with no-slip walls were studied theoretically and using high resolution simulations of 2D reactive Navier-Stokes equations, including the effects of viscosity, thermal conduction, molecular diffusion, real equation of state and a detailed chemical reaction mechanism. It is shown that in "wide" channels (D > 1 mm) there are three distinctive stages of the combustion wave propagation: the initial short stage of exponential acceleration; the second stage of slower flame acceleration; the third stage of the actual transition to detonation. In a thin channel (D < 1 mm) the flame exponential acceleration is not bounded till the transition to detonation. While velocity of the steady detonation waves formed in wider channels (10, 5, 3, 2 mm) is close to the Chapman Jouguet velocity, the oscillating detonation waves with velocities slightly below the CJ velocity are formed in thinner channels (D < 1.0 mm). We analyse applicability of the gradient mechanism of detonation ignition for a detailed chemical reaction model to be a mechanism of the deflagration-to-detonation transition. The results of high resolution simulations are fully consistent with experimental observations of flame acceleration and DDT in hydrogen-oxygen gaseous mixtures.

  • 13.
    Jacobsson, Jesper T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Platzer-Björkman, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edoff, Marika
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    CuInxGa1-xSe2 as an efficient photocathode for solar hydrogen generation2013In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, no 35, p. 15027-15035Article in journal (Refereed)
    Abstract [en]

    Utilizing the energy in the sun to efficiently split water into hydrogen and oxygen can have a huge beneficial impact on a future post-carbon energy system. There is still, however, some way to go before this concept will be fully competitive. At the heart of the problem is finding and designing materials that can drive the photoreaction in an efficient and stable way. In this work we demonstrate how CIGS (CuInxGa1-xSe2), can be used for photo reduction of water into hydrogen. CIGS, which is a proven good solar cell material, does not in itself have the appropriate energetics to drive the reaction to any larger extent. Here we show that by utilizing a solid state pn-junction for charge separation and a catalyst deposited on the surface, the efficiency is significantly improved and photocurrents of 6 mA/cm(2) are demonstrated for the reduction reaction in the configuration of a photo-electrochemical cell. The stability of CIGS in water under illumination turns out to be a problem. In our present set-up, we demonstrate that separation between the charge carrier generation, which takes place in the solar cell, from the catalysis, which takes place in the electrolyte leads to improved stability, while keeping the essential functions of the processes. By incorporating appropriate charge separation layers and optimizing the catalytic conditions at the surface of the electrodes, photocurrents in excess of 20 mA/cm2 are reached for the reduction half reaction, demonstrating how essentially the full potential of GIGS as an efficient absorber material can be utilized in photocatalytic reduction of water into hydrogen.

  • 14.
    Jiao, Mingzhi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Nguyen, Van Duy
    Hanoi Univ Sci & Technol, ITIMS, Hanoi, Vietnam.
    Nguyen, Viet Chien
    Hanoi Univ Sci & Technol, ITIMS, Hanoi, Vietnam.
    Nguyen, Duc Hoa
    Hanoi Univ Sci & Technol, ITIMS, Hanoi, Vietnam.
    Nguyen, Van Hieu
    Hanoi Univ Sci & Technol, ITIMS, Hanoi, Vietnam.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Nguyen, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    On-chip growth of patterned ZnO nanorod sensors with PdO decoration for enhancement of hydrogen-sensing performance2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 25, p. 16294-16304Article in journal (Refereed)
    Abstract [en]

    In this study, we used a low-temperature hydrothermal technique to fabricate arrays of sensors with ZnO nanorods grown on-chip. The sensors on the glass substrate then were sputter decorated with Pd at thicknesses of 2, 4, and 8 nm and annealed at 650 °C in air for an hour. Scanning electron microscopy, high resolution transmission microscopy, X-ray diffraction, and surface analysis by X-ray photoelectron spectroscopy characterization demonstrated that decoration of homogenous PdO nanoparticles on the surface of ZnO nanorods had been achieved. The sensors were tested against three reducing gases, namely hydrogen, ethanol, and ammonia, at 350, 400, and 450 °C. The ZnO nanorods decorated with PdO particles from the 2 and 4 nm layers showed the highest responses to H2 at 450 and 350 °C, respectively. These samples also generally exhibited better selectivity for hydrogen than for ethanol and ammonia at the same concentrations and at all tested temperatures. However, the ZnO nanorods decorated with PdO particles from the 8 nm layer showed a reverse sensing behaviour compared with the first two. The sensing mechanism behind these phenomena is discussed in the light of the spillover effect of hydrogen in contact with the PdO particles as well as the negative competition of the PdO thin film formed between the sensor electrodes during sputter decoration, Pd-Zn heterojunction that forms at high temperature and thus influences the conductivity of the ZnO nanorods.

  • 15.
    Khetkorn, Wanthanee
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry.
    Lindblad, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry.
    Incharoensakdi, Aran
    Enhanced biohydrogen production by the N-2-fixing cyanobacterium Anabaena siamensis strain TISTR 80122010In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 35, no 23, p. 12767-12776Article in journal (Refereed)
    Abstract [en]

    The efficiency of hydrogen production depends on several factors We focused on external conditions leading to enhanced hydrogen production when using the N-2 fixing cyanobacterium Anabaena siamensis TISTR 8012 a novel strain isolated from a rice paddy field in Thailand In this study we controlled key factors affecting hydrogen production such as cell age light intensity time of light incubation and source of carbon Our results showed an enhanced hydrogen production when cells at log phase were adapted under N-2 fixing condition using 0 5% fructose as carbon source and a continuous illumination of 200 mu E m(-2) s(-1) for 12 h under anaerobic incubation The maximum hydrogen production rate was 32 mu mol H-2 mg chl a(-1) h(-1) This rate was higher than that observed in the model organisms Anabaena PCC 7120 Nostoc punctiforme ATCC 29133 and Synechocystis PCC 6803 This higher production was likely caused by a higher nitrogenase activity since we observed an upregulation of nifD The production did not increase after 12 h which was probably due to an increased activity of the uptake hydrogenase as evidenced by an increased hupL transcript level Interestingly a proper adjustment of light conditions such as intensity and duration is important to minimize both the photodamage of the cells and the uptake hydrogenase activity Our results indicate that A siamensis TISTR 8012 has a high potential for hydrogen production with the ability to utilize sugars as substrate to produce hydrogen.

  • 16. Korablov, Dmytro
    et al.
    Ångstrom, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ley, Morten B.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Besenbacher, Flemming
    Jensen, Torben R.
    Activation effects during hydrogen release and uptake of MgH22014In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, no 18, p. 9888-9892Article in journal (Refereed)
    Abstract [en]

    Scandium(II)hydride, ScH2, and scandium(III)chloride, ScCl3, are explored as additives to facilitate hydrogen release and uptake for magnesium hydride. These additives are expected to form more homogeneous composites with Mg/MgH2 as compared to metallic scandium. However, scandium(III)chloride, reacts with MgH2 during mechano-chemical treatment and form ScH2 and MgCl2 (that later crystallise during heat treatment). The composite MgH2-ScH2 was investigated using in-situ synchrotron radiation powder X-ray diffraction during up to five cycles of continuous release and uptake of hydrogen at isothermal conditions at 320, 400 and 450 degrees C and p(H-2) = 100-150 or 10(-2) bar. The data were analysed by Rietveld refinement and no reaction is observed between either MgH2/ScH2 or Mg/ScH2 during cycling. The extracted sigmoidal shaped curves for formation or decomposition of Mg/MgH2 suggest that a nucleation process is preceding the crystal growth. The reaction rate increases with increasing number of cycles of hydrogen release and uptake at isothermal conditions possibly due to activation effects. This kinetic enhancement is strongest between the first cycles and may be denoted an activation effect. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  • 17. Leino, Hannu
    et al.
    Shunmugam, Sumathy
    Isojarvi, Janne
    Oliveira, Paulo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Mulo, Paula
    Saari, Lyudmila
    Battchikova, Natalia
    Sivonen, Kaarina
    Lindblad, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Aro, Eva-Mari
    Allahverdiyeva, Yagut
    Characterization of ten H-2 producing cyanobacteria isolated from the Baltic Sea and Finnish lakes2014In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, no 17, p. 8983-8991Article in journal (Refereed)
    Abstract [en]

    The genetic background and activities of the enzymes involved in H-2 production were investigated from ten distinct H-2 producing cyanobacteria, revealed by a recent screening. All strains are N-2-fixing, filamentous and heterocystous. Southern hybridization revealed that the tested strains possess the genes encoding the conventional nitrogenase (nifHDK1), and lack the alternative nitrogenases. The high H-2 production rate of these strains was shown not to be dependent on the presence of highly active nitrogenase or bidirectional hydrogenase enzymes. Moreover, most of the strains possessed a highly active uptake hydrogenase enzyme. We also examined the structure of the nif and hup operons encoding nitrogenase and uptake hydrogenase enzymes in the Calothrix 336/3 strain, the best H-2 producer in the screening. We concluded that the ability of the cyanobacteria to produce high levels of H-2 is not directly linked to the maximum capacities of the enzymes involved in H-2 production.

  • 18.
    Liu, Peng
    et al.
    Department of Materials and Engineering, The Royal Institute of Technology (KTH).
    Nisar, Jawad
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Pathak, Biswarup
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hybrid density functional study on SrTiO3 for visible light photocatalysis2012In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, no 16, p. 11611-11617Article in journal (Refereed)
    Abstract [en]

    Hybrid Density Functional calculations have been performed on the electronic structure of anionic mono- (S, N, P, and C) and co-doped (N-N, N-P, N-S, P-P) SrTiO3 to improve their visible light photocatalytic activity. The electronic band position of doped system has been aligned with respect to the water oxidation/reduction potential. The electronic band position and optical absorption study shows that the mono- (S) and co-doped (N-N, N-P and P-P) SrTiO3 systems are promising materials for the visible-light photocatalysis. The calculated binding energies show that the co-doped systems are more stable than their respective mono-doped systems.

  • 19.
    Liu, Si
    et al.
    Shaanxi Normal Univ, Key Lab Macromol Sci Shaanxi Prov, Sch Chem & Chem Engn, Xian 710119, Shaanxi, Peoples R China.
    Lei, You-Jia
    Shaanxi Normal Univ, Key Lab Macromol Sci Shaanxi Prov, Sch Chem & Chem Engn, Xian 710119, Shaanxi, Peoples R China.
    Xin, Zhi-Juan
    Shaanxi Normal Univ, Key Lab Macromol Sci Shaanxi Prov, Sch Chem & Chem Engn, Xian 710119, Shaanxi, Peoples R China.
    Xiang, Rui-Juan
    Shaanxi Normal Univ, Key Lab Macromol Sci Shaanxi Prov, Sch Chem & Chem Engn, Xian 710119, Shaanxi, Peoples R China.
    Styring, Stenbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Thapper, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Wang, Hong-Yan
    Shaanxi Normal Univ, Key Lab Macromol Sci Shaanxi Prov, Sch Chem & Chem Engn, Xian 710119, Shaanxi, Peoples R China.
    Ligand modification to stabilize the cobalt complexes for water oxidation2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 50, p. 29716-29724Article in journal (Refereed)
    Abstract [en]

    Ligand modifications with electron-withdrawing and electron-donating groups were applied to afford three novel mononuclear cobalt-based catalysts [Co(TPA-R)]2+ (TPA = tris(2-pyridylmethyl) amine; R = tri-α F, 1; R = tri-αOMe, 2; R = mono-αF, 3) for water oxidation. Characterization of the catalysts shows that steric and electronic factors play important roles in inhibiting spontaneous intermolecular dimerization of two cobalt centers, and influence the catalytic behavior. Complex 1 exhibits the best catalytic ability and stability, showing a good efficiency with TOF of 6.03 ± 0.02 mol (O2)/(mol (cat)*s) in photo-induced water oxidation experiments using Ru (bpy)3 2+ as photosensitizer and Na2S2O8 as electron acceptor. The bulky electron donating groups in 2 led to degradation of the complex and formation of CoOx particles acting as the real catalyst. Electron-withdrawing substituents on the TPA ligand can stabilize the catalyst under both electrochemical and photo-induced conditions, with the enhancement increasing with the number of the electron-withdrawing groups. © 2017 Hydrogen Energy Publications LLC.

  • 20.
    Maark, Tuhina Adit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hussain, Tanveer
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Structural, electronic and thermodynamic properties of Al- and Si-doped alpha-, gamma-, and beta-MgH2: Density functional and hybrid density functional calculations2012In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, no 11, p. 9112-9122Article in journal (Refereed)
    Abstract [en]

    In this work, we present a detailed study of Al- and Si-doped alpha-, gamma-, and beta-MgH2 phases using the gradient corrected density functional GGA-PBE and the hybrid Hartree-Fock density functionals PBE0 and HSE06 within the framework of generalized Kohn-Sham density functional theory (DFT) using a plane-wave basis set. We investigate the structural, electronic, and thermodynamical properties of these compounds with regard to their hydrogen storage effectiveness. PBE0 and HSE06 predict cell parameters and bond lengths that are in good agreement with the GGA-PBE calculations and previously known experimental results. As expected smaller band gaps (E(g)s) are predicted by GGA-PBE for the pure magnesium hydride phases. PBE0 overcomes the deficiencies of DFT in treating these materials better than HSE06 and yields E(g)s that compare even better with previous GW calculations. Both the hybrid functionals increase the E(g)s of the Al-doped magnesium hydrides by much less magnitudes than of the Si-doped phases. This difference is interpreted in terms of charge density distributions. Best H-2 adsorption energies (Delta H-ads) are computed by HSE06 while GGA-PBE significantly overestimates them. Si-doped alpha- and beta-MgH2 exhibited the least negative Delta H-ads in close proximity to the H-2 binding energy range of -0.21 to -0.41 eV ideal for practical H-2 storage transportation applications.

  • 21. Maneeruttanarungroj, Cherdsak
    et al.
    Lindblad, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry.
    Incharoensakdi, Aran
    A newly isolated green alga, Tetraspora sp. CU2551, from Thailand with efficient hydrogen production2010In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 35, no 24, p. 13193-13199Article in journal (Refereed)
    Abstract [en]

    A novel unicellular hydrogen-producing green alga was isolated from fresh water pond in Pathumthani province, Thailand. Under light microscope, this alga was identified as belonging to the genus Tetraspora. Phylogenetic analysis of 18S rRNA sequence revealed that the green alga, identified as Tetraspora sp. CU2551, is closely related to other unicellular green algal species. Tetraspora sp. CU2551 had the shortest doubling time when grown in Tris-acetate-phosphate (TAP) medium under a light intensity of 48-92 mu E/m(2)/s and a temperature of 36 C. Hydrogen production increased with increasing pH from 5.75 to 9.30; however, almost no production was observed at a pH of 5.25. Addition of 0.5 mM P-mercaptoethanol to the TAP medium stimulated hydrogen production about two-fold. During the hydrogen production phase, the use of TAP medium lacking both nitrogen and sulfur resulted in about 50% increase in the hydrogen production. This was in contrast to only a small increase in the production when either nitrogen or sulfur was omitted in TAP medium. The stimulation of hydrogen production by 0.5 mM beta-mercaptoethanol under nitrogen- and sulfur-deprived conditions occurred only when the cells were grown at a light intensity lower than 5 mu E/m(2)/s with no effects at higher intensities. Maximal calculated hydrogen production, 17.3-61.7 mu mol/mg Chl a/h, is a very high production rate compared to other green algae and makes Tetraspora sp. CU2551 an interesting model strain for photobiological hydrogen production.

  • 22. Maneeruttanarungroj, Cherdsak
    et al.
    Lindblad, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Incharoensakdi, Aran
    Sulfate permease (SulP) and hydrogenase (HydA) in the green alga Tetraspora sp CU2551: Dependence of gene expression on sulfur status in the medium2012In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, no 20, p. 15105-15116Article in journal (Refereed)
    Abstract [en]

    The newly identified chloroplast envelope-localized sulfate permease gene (sulP) and the hydrogenase gene (hydA) from the green alga Tetraspora sp. CU2551 are reported in this study. The sulP showed an open reading frame of 1014 bp with the 5'- and 3'-UTR being 285 and 225 bp, respectively. The deduced amino acid sequence of SulP revealed an extended N-terminus where the putative chloroplast transit peptide was identified. This suggests a close relationship between Tetraspora and Chlamydomonas reinhardtii SulPs, as confirmed by phylogenetic tree analysis. In addition, the Tetraspora hydA was identified. The cDNA sequence showed an 878 bp encoding 292 amino acid residues. The deduced amino acid sequence of Tetraspora HydA is closely related to HydA of Chlorella fusca. The transcript levels of both sulP and hydA of Tetraspora showed an up-regulation of about 2.3 times after sulfur deprivation, whereas upon sulfur repletion the expression of both genes decreased. The production of H-2 and PSII activity decreased in cells grown under sulfur-deprived condition. These two activities could be restored when the cells were transferred to the medium supplemented with sulfur. Our results demonstrate a different response to sulfur deprivation between C. reinhardtii and Tetraspora sp. CU 2551.

  • 23.
    Molinari, Alan
    et al.
    Karlsruhe Inst Technol, Inst Nanotechnol, D-76021 Karlsruhe, Germany..
    D'Amico, Federico
    Univ Bologna, Dept Phys & Astron, I-40126 Bologna, Italy..
    Calizzi, Marco
    Univ Bologna, Dept Phys & Astron, I-40126 Bologna, Italy..
    Zheng, Yan
    Ilmenau Univ Technol, Inst Phys, Ilmenau, Germany..
    Boelsma, Christiaan
    Delft Univ Technol, Dept Chem Engn, NL-2600 AA Delft, Netherlands..
    Mooij, Lennard
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Delft Univ Technol, Dept Chem Engn, NL-2600 AA Delft, Netherlands..
    Lei, Yong
    Ilmenau Univ Technol, Inst Phys, Ilmenau, Germany..
    Hahn, Horst
    Karlsruhe Inst Technol, Inst Nanotechnol, D-76021 Karlsruhe, Germany..
    Dam, Bernard
    Delft Univ Technol, Dept Chem Engn, NL-2600 AA Delft, Netherlands..
    Pasquini, Luca
    Univ Bologna, Dept Phys & Astron, I-40126 Bologna, Italy..
    Interface and strain effects on the H-sorption thermodynamics of size-selected Mg nanodots2016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 23, p. 9841-9851Article in journal (Refereed)
    Abstract [en]

    This work deals with the thermodynamics of hydride formation in 3-D nanoconfined Mg. Two ensembles of nearly monodisperse Mg nanodots (NDs) with different diameters (60 and 320 nm), were grown by the template nanopatterning method, using ultra-thin alumina membranes (UTAMs) with ordered porosity as evaporation masks. Multilayer NDs consisting of 30 nm Mg, 5 nm Ti and 5 nm Pd were deposited on UTAM-coated glass substrates by molecular beam epitaxy. The lateral surface of the NDs is constituted by native MgO. The morphology of the NDs was characterized by field emission scanning electron microscopy and atomic force microscopy. Hydride formation and decomposition was studied at low temperature (363-393 K) by means of optical hydrogenography. Compared to bulk Mg, the plateau pressure for hydrogen absorption in NDs exhibits an upward shift, which is larger for small NDs. Differently, the desorption plateau pressure is almost the same for the two NDs size and is lower than for bulk Mg. These hydrogen sorption features are discussed in the frame of a model that takes into account both interface energy and elastic strain energy in the constrained nanodots. The onset of plastic deformation, marked by a high pressure hysteresis between hydrogen absorption and desorption isotherms, limits the extent of hydride destabilization that can be achieved by elastic strain engineering.

  • 24.
    Mooij, Lennard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Perkisas, Tyche
    Pálsson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Schreuders, Herman
    Wolff, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Bals, Sara
    Dam, Bernard
    The effect of microstructure on the hydrogenation of Mg/Fe thin film multilayers2014In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, no 30, p. 17092-17103Article in journal (Refereed)
    Abstract [en]

    Nanoconfined magnesium hydride can be simultaneously protected and thermodynamically destabilized when interfaced with materials such as Ti and Fe. We study the hydrogenation of thin layers of Mg (<14 nm) nanoconfined in one dimension within thin film Fe/Mg/Fe/Pd multilayers by the optical technique Hydrogenography. The hydrogenation of nanosized magnesium layers in Fe/Mg/Fe multilayers surprisingly shows the presence of multiple plateau pressures, whose nature is thickness dependent. In contrast, hydrogen desorption occurs via a single plateau which does not depend on the Mg layer thickness. From structural and morphological analyses with X-ray diffraction/reflectometry and cross-section TEM, we find that the Mg layer roughness is large when deposited on Fe and furthermore contains high-angle grain boundaries (GB's). When grown on Ti, the Mg layer roughness is low and no high-angle GB's are detected. From a Ti/Mg/Fe multilayer, in which the Mg layer is flat and has little or no GB's, we conclude that MgH2 is indeed destabilized by the interface with Fe. In this case, both the ab- and desorption plateau pressures are increased by a factor two compared to the hydrogenation of Mg within Ti/Mg/Ti multilayers. We hypothesize that the GB's in the Fe/Mg/Fe multilayer act as diffusion pathways for Pd, which is known to greatly alter the hydrogenation behavior of Mg when the two materials share an interface. 

  • 25.
    Nisar, Jawad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Wang, Baochang
    Araujo, Carlos Moyses
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    da Silva, Antonio Ferreira
    Kang, Tae Won
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Band gap engineering by anion doping in the photocatalyst BiTaO4: First principle calculations2012In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, no 4, p. 3014-3018Article in journal (Refereed)
    Abstract [en]

    We have shown the effect of mono and co-doping of non-metallic anion atoms on the electronic structure in BiTaO4 using the first-principles method. It can improve the photocatalytic efficiency for hydrogen production in the presence of visible sunlight. It is found that the band gap of BiTaO4 has been reduced significantly up to 54% with different nonmetallic doping. Electronic structure analysis shows that the doping of nitrogen is able to reduce the band gap of BiTaO4 due to the impurity N 2p state at the upper edge of the valence band. In case of C or C-S doped BiTaO4, double occupied (filled) states have been observed deep inside the band gap of BiTaO4. The large reduction of band gap has been achieved, which increases the visible light absorption. These results indicate that the doping of non-metallic element in BiTaO4 is a promising candidate for the photocatalyst due to its reasonable band gap.

  • 26.
    Pasti, Igor A.
    et al.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Leetmaa, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala Univ, Dept Phys & Astron, Box 516, S-75120 Uppsala, Sweden..
    Skorodumova, Natalia V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Multiscale Mat Modelling Grp, Brinellvagen 23, S-10044 Stockholm, Sweden..
    General principles for designing supported catalysts for hydrogen evolution reaction based on conceptual Kinetic Monte Carlo modeling2016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 4, p. 2526-2538Article in journal (Refereed)
    Abstract [en]

    Rational catalyst design presents one of the main paradigms in the contemporary materials science. Although the electronic structure calculations can be used to search for possible candidates, realistic supported catalysts are difficult to address in this way. In this contribution we use conceptual model of the supported hydrogen evolution reaction (HER) catalyst and investigate possible processes using Kinetic Monte Carlo simulations. In specific, we look at the possibility to boost H-2 production by the H spillover to the support and the tailoring of the catalyst deposit. Different scenarios were considered depending on the nature of the HER rate determining step (RDS) on the catalyst surface and the effects of the rates of elementary processes, catalyst dispersion and morphology are analyzed. Metals with low affinity towards hydrogen should be used as catalyst supports, while H spillover can boost H-2 production if Tafel or Heyrovsky reaction is the RDS on the catalyst surface. However, this can be achieved only if the catalyst dispersion is high, while the support has to act as a Hads acceptor and enable fast Hads recombination. General instructions for the choice of the catalystlsupport combination can be used to design new advanced HER catalysts.

  • 27.
    Qian, Zhao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Pathak, Biswarup
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Energetic and structural analysis of N2H4BH3 inorganic solid and its modified material for hydrogen storage2013In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, no 16, p. 6718-6725Article in journal (Refereed)
    Abstract [en]

    Here we have exposed the electronic structure, chemical bonding of the light-weight N2H4BH3 inorganic material for hydrogen storage applications and analyzed its hydrogen removal energetics using state-of-the-art first-principles method. The mechanism for the H-host bond weakening in this kind of solid has also been explored. It is shown that the electronic density of states of N(2)H(4)BH(3)d solid near the Fermi level is mainly contributed by the B p-states, H (B) s-states, and the end N p-states. The calculated smallest hydrogen removal energy of N2H4BH3 solid is 4.16 eV. One Li-modified structure has been obtained through ab initio relaxations and its hydrogen removal energies are found dramatically decreased by as much as 50% compared with those of pristine N2H4BH3 solid. The B-H bond weakening is attributed to the elongation of the bond length; for the N H bonds, the weakening is found to be due to the destabilization of N-H bonds before hydrogen removal and the stabilization of residual N-H bond after hydrogen removal. The weakening of these bonds is of great significance for the improvement of hydrogen desorption kinetics of the material. We propose this study should help to deepen understanding of properties of N2H4BH3 inorganic solid and its related materials for hydrogen storage applications and guide experimentalists and engineers to develop better candidate materials for the advance of the field.

  • 28.
    Qiu, Zhen
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ma, Yue
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Controlled crystal growth orientation and surface charge effects in self-assembled nickel oxide nanoflakes and their activity for the oxygen evolution reaction2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 47, p. 28397-28407Article in journal (Refereed)
    Abstract [en]

    Although sustainable hydrogen production from solar energy is a promising route for the future, the cost of the necessary photovoltaic and photoelectrochemical devices as well as a lack of detailed understanding and control of catalyst interfaces in nanomaterials with high catalytic activity are the largest impediments to commercial implementation. Here, we report how a higher catalytic efficiency can be achieved by utilizing an earth-abundant Nickel oxide (NiO) catalyst via an improved control of the crystalline growth orientation and self-assembly. The relationship between the surface charge and the morphology of the nano-catalysts is investigated using a hydrothermal method where the pH is utilized to control both the crystal growth direction and crystallization of Ni(OH)2 and eventually in NiO, where the self-assembly properties of nanoflakes (NFs) into hierarchical flower-like nickel oxide NFs depend on balancing of forces during synthesis. The surface charge ofthe NiO at different pH values was measured with electrophoretic dynamic light scattering (EDLS) and is known to be closely related to that of Ni(OH)2 and is here utilized to control the relative change in the surface charge in the precursor solution. By preparing NiO NFs under variation of the pH conditions of the precursor Ni(OH)2 system, the surface energies of exposed lattice planes of the growing nanostructures can be altered and an enhanced crystal growth orientation in a different direction can be controlled. Specifically, the [111] and [220] growth orientation in cubic NiO can be favored or suppressed with respect to the [200] direction. Benefiting from the large surface area provided by the mesoporous NiO NFs, the catalyst electrode exhibits high activity toward the oxygen evolution reactions in alkaline electrolyte. The NiO nanostructure synthesized at pH 10 displays oxygen evolution reaction (OER) overpotential of 0.29 V and 0.35 V versus the reversible hydrogen electrode (RHE) at 1 mA cm2 and 10 mA cm2 current density, respectively. This is compared to commercial NiO with more than 0.15 V additional overpotential and the same or lower overpotential compared to RuO2 and IrO2 at alkaline conditions. The results show that the OER catalytic activity can be drastically increased by a detailed control of the crystal growth orientation and the self-assembly behavior where the active surface charge around the point of zero charge during synthesis of the metal hydroxides/oxides is introduced as an important design principle for producing efficient electrocatalysts.

  • 29.
    Ramzan, Muhammad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Lebègue, S.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Transition metal doped MgH2: a material to potentially combine fuel-cell and battery technologies2010In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 35, no 19, p. 10373-10376Article in journal (Refereed)
    Abstract [en]

    MgH2 is studied as a negative electrode material for rechargeable batteries on the basis of density functional theory calculations. We calculate the average voltage of the corresponding Li-ion battery, which is in good agreement with the experimental value, and we predict the average voltage for the Na-ion battery. Then, molecular dynamics simulations are used to study the diffusive properties of lithium in MgH2 clusters. In particular, we dope MgH2 with transition metals (Fe, Ni, Ti, and V), and analyze the effect on the diffusion of lithium, which is shown to be essentially unaffected. Therefore, we propose that transition metal doped MgH2 is a material that can be used efficiently in both batteries and fuel-cell technologies.

  • 30.
    Risch, Marcel
    et al.
    Freie Universität Berlin, Institut für Experimentalphysik.
    Shevchenko, Denys
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Anderlund, Magnus F.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Styring, Stenbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Heidkamp, Jonathan
    Freie Universität Berlin, Institut für Experimentalphysik.
    Lange, Kathrin M.
    Helmholtz-Zentrum Berlin für Materialien und Energie.
    Thapper, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Zaharieva, Ivelina
    Freie Universität Berlin, Institut für Experimentalphysik.
    Atomic structure of cobalt-oxide nanoparticles activein light-driven catalysis of water oxidation2012In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, no 10, p. 8878-8888Article in journal (Refereed)
    Abstract [en]

    The atomic structure of water-oxidizing nanoparticles (10-60 nm) formed from cobalt(II)salts and methylenediphosphonate (M2P) is investigated. These amorphous nanoparticles are of high interest for production of solar fuels. They facilitate water oxidation in a directly light-driven process using [Ru(bpy)3]2+ (bpy = 2,2’-bipyridine) as a photosensitizer and persulfate (S2O82-) as an electron acceptor. By X-ray absorption spectroscopy (XAS) at the cobalt K-edge, cobalt L-edge and oxygen K-edge, we investigate the light-driven transition from the CoII/M2P precursor to the active catalyst, which is a layered cobalt(III) oxide with structural similarities to water-oxidizing electrocatalysts. The M2P ligand likely binds at the periphery of the nanoparticles, preventing their further agglomeration during the catalytic reaction. This system opens a possibility to link the catalytically active nanoparticles via a covalent bridge to a photosensitizer and build an artificial photosynthetic system for direct utilization of solar energy for fuel production without production of electricity as an intermediate step.

  • 31.
    Shen, Yang
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Peng, Fei
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Kontos, Sofia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Noreus, Dag
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Improved NiMH performance by a surface treatment that creates magnetic Ni-clusters2016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 23, p. 9933-9938Article in journal (Refereed)
    Abstract [en]

    A surface treatment method has been developed to activate the surface of an AB(5) type (La-20 Ce-7 Pr-1 Nd-4 Al-2 Mn-5 Co-6 Ni-55) alloy. In the process the surface is covered with a porous surface layer containing needle shaped rare earth hydroxides after etching by a potassium hydroxide solution. TEM studies show in addition the presence of a denser surface oxide layer with embedded Ni containing clusters covering the bulk alloy. The magnetic properties of the alloy powders change with the surface treatment. In addition to a paramagnetic component of the bulk alloy, surface treated alloy also displays superparamagnetic and ferromagnetic properties. In electrochemical half-cell tests, the alloy shows better high-rate dischargeability with increasing presence of magnetic clusters in the metal hydride particles surface.

  • 32.
    Singh, Deobrat
    et al.
    SV Natl Inst Technol, Dept Appl Phys, Adv Mat Lab, Surat 395007, India..
    Gupta, Sanjeev K.
    St Xaviers Coll, Dept Phys, Computat Mat & Nanosci Grp, Ahmadabad 380009, Gujarat, India..
    Sonvane, Yogesh
    SV Natl Inst Technol, Dept Appl Phys, Adv Mat Lab, Surat 395007, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    High performance material for hydrogen storage: Graphenelike Si2BN solid2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 36, p. 22942-22952Article in journal (Refereed)
    Abstract [en]

    Recently, two dimensional graphenelike i.e. Si2BN solid monolayer have attracted much attention for the use of hydrogen developments. The work is based on first principles calculations using density functional theory with long range van der Waal (vdW) interactions. The optimized structure is energetically more stable due to high formation energy 45.39 eV with PBE and 50.82 eV with HSE06 functionals, respectively. Our ab-initio studies show that Pd (palladium) adatoms secured graphenelike Si2BN solid via two types of interactions; physisorption and chemisorptions reactions, which engrossing up to 3H(2) molecules signifying gravimetric limits of approximate to 6.95-10.21 wt %. The absorption energies vary from -0.31 eV to -1.93 eV with Pd-adatom and without Pd-adatom respectively, and it varies up to -1.24 eV. The work function of pure Si2BN is 5.36 eV while metal-adatom on monolayer Si2BN with (1 to 6)H-2 molecules is 3.53 eV -4.99 eV and reaches up to 5.85 eV. The theoretical study suggests that the functionalized graphenelike Si2BN is efficient for hydrogen storage and propose a possible improvement for advantageous storage of hydrogen at ambient conditions.

  • 33.
    Skjanes, Kari
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Knutsen, Gjert
    Kallqvist, Torsten
    Lindblad, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    H2 production from marine and freshwater species of green algae during sulfur deprivation and considerations for bioreactor design2008In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 33, no 2, p. 511-521Article in journal (Refereed)
    Abstract [en]

    Twenty-one species of green algae isolated from marine, freshwater and terrestrial environments were screened for the ability to produce H-2 under anaerobic conditions. Seven strains found positive for H-2 production under anaerobic conditions were also screened for the ability to produce H-2 under sulfur (S) deprivation. In addition to the traditional model species Chlamydomonas reinhardtii, C. noctigama (freshwater) and C. euryale (brackish water) were able to produce significant amounts of H-2 under S-deprivation. These species were also able to utilize acetate as a substrate for growth in light. The S-deprivation experiments were performed under photoheterotrophic conditions in a purpose-specific designed bioreactor, and it was shown that an automated pH adjustment feature was essential to maintain a stable pH in the cultures. Several materials commonly used in bioreactors, such as rubber materials, plastics and steel alloys, had a negative effect on the survival of S-deprived algae cultures. Unexpectedly, traces of H-2 were produced under S-deprivation during O-2 saturation in the cultures, possibly derived from local anaerobic environments formed in algal biofilms on the membranes covering the O-2 electrodes.

  • 34.
    Skjånes, Kari
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry.
    Lopes Pinto, Fernando
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry.
    Lindblad, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Microbial Chemistry.
    Evidence for transcription of three genes with characteristics of hydrogenases in the green alga Chlamydomonas noctigama2010In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 35, no 3, p. 1074-1088Article in journal (Refereed)
    Abstract [en]

    Some green algae have shown the ability to produce hydrogen under anaerobic conditions. The production of hydrogen in green algae is catalyzed by hydrogenases, which are small monomeric enzymes with high conversion efficiency and high oxygen sensitivity. Most green algae analyzed to date where hydrogenase genes are detected, have been shown to contain two distinct hydrogenases. However, very little is known about which functions the two different enzymes represent. There are also many unknowns within the mechanisms behind hydrogen production as to the roles hydrogenases play under different conditions, and consequently also about the potential for optimization of a hydrogen production process which could be found in this respect. This study focuses on the possibility for the presence of more than two hydrogenases in a single green alga. A large number of degenerate primers were designed and used to produce 3′-RACE products, which in turn were used to design gene specific primers used for PCR and 5′-RACE reactions. The sequences were aligned with known algal hydrogenases to identify products which had homology to these. Products where homology was identified were then explored further. A high number of clones from each band were sequenced to identify products with similar lengths which would not show up as separate bands on a gel. Sequences found to have homology with algal hydrogenases were translated into putative amino acid sequences and analyzed further to obtain detailed information about the presence of specific amino acids with known functions in the enzyme. This information was used to evaluate the likelihood of these transcripts coding for true hydrogenases, versus hydrogenase-like or narf-like proteins. We here present evidence showing that Chlamydomonas noctigama is able to transcribe three genes which share a significant number of characteristics with other known algal FeFe-hydrogenases. The three genes have been annotated HYDA1, HYDA2 and HYDA3.

  • 35.
    Srepusharawoot, Pornjuk
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Blomqvist, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Araújo, Moysés
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Scheicher, Ralph
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hydrogen Binding in Alkali-decorated Iso-reticular Metal Organic Framework-16 based on Zn, Mg, and Ca2011In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 36, no 1, p. 555-562Article in journal (Refereed)
    Abstract [en]

    Hydrogen adsorption energies were investigated in three different types of iso-reticular Metal Organic Framework-16, Zn-/Mg-/Ca-MOF16, decorated with either Li, Na, or K. Concerning the binding strengths of the alkali metals, the density functional theory calculations reveal that Li is bound strongest to the host framework, followed by K and Na. Decoration with Li also results in the highest hydrogen adsorption energies among the studied alkali metals. Furthermore, Zn-MOF16 exhibits the highest hydrogen adsorption energies near the metal oxide cluster, while hydrogen binding strengths at organic linker sites do not differ substantially between Zn-/Mg-/Ca-MOF16. Based on these results, we conclude that for Metal Organic Framework-16, Li-decorated Zn-MOF16 appears to be the optimal choice for hydrogen storage among the nine combinations.

  • 36. Srepusharawoot, Pornjuk
    et al.
    Swatsitang, Ekaphan
    Amornkitbamrung, Vittaya
    Pinsook, Udomsilp
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hydrogen adsorption of Li functionalized Covalent Organic Framework-366: An ab initio study2013In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, no 33, p. 14276-14280Article in journal (Refereed)
    Abstract [en]

    This work deals with the investigations of hydrogen adsorption energies of the Li functionalized Covalent Organic Framework-366 (COF-366) by using the density functional theory method. Based on total energy calculations, it was found that Li atom is preferentially trapped at the center site of the tetra(p-amino-phenyl) porphyrin and the onN site of a terephthaldehyde chain. Moreover, hydrogen adsorption energies per H-2 for 1-3 H-2 loadings range from 0.03 to 0.22 eV. According to ab initio molecular dynamics simulations, our results found that hydrogen capacities of Li functionalized COF-366 at ambient pressure are 2.06, 1.58, and 1.05 wt% for 77, 150 and 298 K, respectively.

  • 37.
    Zhang, Wei
    et al.
    Hubei Univ, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Fac Phys & Elect Sci, Wuhan 430062, Hubei, Peoples R China..
    Cai, Yixiao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wang, Baoyuan
    Hubei Univ, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Fac Phys & Elect Sci, Wuhan 430062, Hubei, Peoples R China.;Royal Inst Technol, Dept Energy Technol, SE-10044 Stockholm, Sweden..
    Deng, Hui
    Hubei Univ, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Fac Phys & Elect Sci, Wuhan 430062, Hubei, Peoples R China..
    Feng, Chu
    Hubei Univ, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Fac Phys & Elect Sci, Wuhan 430062, Hubei, Peoples R China..
    Dong, Wenjing
    Hubei Univ, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Fac Phys & Elect Sci, Wuhan 430062, Hubei, Peoples R China..
    Li, Junjiao
    Nanjing Yunna Nanotech Ltd, Heyan Rd 271, Nanjing 210037, Jiangsu, Peoples R China..
    Zhu, Bin
    Hubei Univ, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Fac Phys & Elect Sci, Wuhan 430062, Hubei, Peoples R China.;Royal Inst Technol, Dept Energy Technol, SE-10044 Stockholm, Sweden..
    The fuel cells studies from ionic electrolyte Ce0.8Sm0.05Ca0.15O2-delta to the mixture layers with semiconductor Ni0.8Co0.15Al0.05LiO2-delta2016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 41, p. 18761-18768Article in journal (Refereed)
    Abstract [en]

    The mixture of ionic electrolyte Ce0.8Sm0.05Ca0.15O2-delta (SCDC) and semiconductor Ni0.8Co0.15Al0.05LiO2-delta (NCAL) layers was used for low temperature solid oxide fuel cell (LT-SOFC) applications. Using the as-prepared SCDC-NCAL semiconductor-ionic layer to replace the ionic SCDC electrolyte, following results have been obtained: the SCDC electrolyte fuel cell reached a lower voltage, 1.05 V, and lower power output, 415 mW cm(-2), compared to that using the semiconductor-ionic layer, 1.06 V and 617 mW cm(-2) at 550 degrees C. The electrochemical impedance spectroscopy (EIS) was applied to investigate the electrochemical processes of the device; X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) for the microstructure and morphology of the as-prepared materials. The results have illuminated that the introduction of semiconductor into ionic electrolyte could make extended triple phase boundary (TPB) area, which can provide more active sites to accelerate the fuel cell reactions and enhance the cell performance. Furthermore, we also discovered that the ionic SCDC and electronic NCAL should be in an appropriate composition to achieve a balanced ionic and electronic conductivity, which is the key issue for high performance semiconductor-ionic fuel cells.

  • 38.
    Zhang, Wei
    et al.
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Cai, Yixiao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Royal Inst Technol, Dept Energy Technol, SE-10044 Stockholm, Sweden..
    Wang, Baoyuan
    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..
    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..
    Dong, Wenjing
    Hubei Univ, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Hubei, Peoples R China..
    Li, Junjiao
    Nanjing Yunna Nanotech Ltd, Heyan Rd 271, Nanjing 210037, Jiangsu, 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..
    Mixed ionic-electronic conductor membrane based fuel cells by incorporating semiconductor Ni0.8Co0.15Al0.05LiO2-delta into the Ce0.8Sm0.2O2-delta-Na2CO3 electrolyte2016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 34, p. 15346-15353Article in journal (Refereed)
    Abstract [en]

    In the present study, a novel composite was fabricated by incorporating the semiconductor Ni0.8Co0.15Al0.05LiO2-delta (NCAL) into the ionic electrolyte Ce0.8Sm0.2O2-delta-Na2CO3 (NSDC), and further developed as a mixed-conducting membrane for single layer fuel cell (SLFC) applications. Experimentally, the crystal structure, morphology, chemical composition and thermo-stability of the composite were characterized by XRD, SEM and TGA. The best cell performance was investigated when the NSDC-NCAL membrane was optimized at a weight ratio of 6:4. On this basis, a number of interesting findings were obtained: i) the mixed conducting membrane did not cause any short circuit; on the contrary, the cell reached a decent open circuit voltage (OCV) of similar to 1.0 V. a high power density of 1072 mW cm(-2) was achieved at 550 degrees C for the NSDC-NCAL membrane based cell, which was much better than that using a pure NSDC electrolyte membrane. Electrochemical impedance spectroscopy (EIS) showed that the NSDC-NCAL composite exhibited significantly improved grain boundary conduction and reduced electrode polarizations, contributing to the resultant performance. To consolidate the usefulness of the device, we also conducted the durability test. The above findings indicate the strategy of introducing mixed NSDC-NCAL membrane is feasible for high-performance SLFCs operating at low temperatures.

  • 39.
    Zhao, Yufeng
    et al.
    Dept of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao, Kina.
    Wang, Wei
    Dept of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao, Kina.
    Xiong, Ding-Bang
    Dept of Materials Science and Engineering, Kyoto University, Tokyo, Japan.
    Shao, Guangjie
    Dept of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao, Kina.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Yu, Shengxue
    Dept of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao, Kina.
    Gao, Faming
    Dept of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao, Kina.
    Titanium carbide derived nanoporous carbon for supercapacitor applications2012In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 37, no 24, p. 19395-19400Article in journal (Refereed)
    Abstract [en]

    Carbide derived carbons (CDCs) are porous carbons produced by extraction metals from metal carbides. In this paper, nanoporous carbon with large surface area of above 1000 m2/g has been prepared by thermo-chemical etching of titanium carbide (TiC) in chlorine atmosphere. An improved design of accurate control on the reaction time with high yield percentage above 98% is reported. Transmission electron microscope (TEM) and X-ray diffraction (XRD) analysis showed the existence of ordered graphite phase in this mostly amorphous titanium carbide derived carbon (TiC-CDC), and the degree of ordering increased with chlorination temperature. Raman spectra study demonstrated that the TiC-CDC consisted of both D-band and G band of graphitic carbon, and the ratio of the integrated intensities ID/IG decreased with chlorination temperature. T-plot nitrogen sorption measurements proved the co-existence of micropores (<2 nm) and mesopores (2–50 nm), while the highest specific surface area was achieved from sample synthesized at 400 °C. Cyclic voltammetry measurements on the TiC-CDC did not show any major Faradic reactions within the experimental voltage range. A specific capacitance of 138.3 F/g was achieved from sample synthesized at 400 °C. The specific capacitance increased with increasing the amount of microporous area.

  • 40. Zheng, Jing-Jing
    et al.
    Wang, Bao-Tian
    Di Marco, Igor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Li, Wei-Dong
    Electronic structure and phase stability of plutonium hydrides: Role of Coulomb repulsion and spin-orbital coupling2014In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, no 25, p. 13255-13265Article in journal (Refereed)
    Abstract [en]

    The electronic and magnetic states, chemical bonding and reactions, and phonon spectrum of the plutonium hydrides Puliz (x = 2, 3) are investigated by employing first-principles calculations by means of the density functional theory (DFT) + U approach. The strong correlation and the spin-orbit coupling (sac) effects on these 5f electrons systems are systematically studied. Results show that both the strong correlation and the SOC play critical roles in correctly describing their ground-state properties. The antiferromagnetic configuration of PuH2 is found energetically most stable while for PuH3 the ferromagnetic state is the most stable state. Our calculated phonon spectra clearly indicate the dynamical stability of these magnetic configurations. For PuH3, more electrons from the Pu atoms are released to bond with H than that in PuH2. As a result, the lattice constant is contracted by increasing the H concentration. Reacting from metal Pu and molecule H-2, more PuH3 should be produced than PuH2 in low temperature condition. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  • 41.
    Ångström, Jonas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Johansson, Robert
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Rude, Line Holdt
    Gundlach, Carsten
    Scheicher, Ralph H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Jensen, Torben R.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hydrogen storage properties of the pseudo binary Laves phase (Sc1-xZrx)(Co1-yNiy)2 system2013In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, no 23, p. 9772-9778Article in journal (Refereed)
    Abstract [en]

    The (Sc1-xZrx)(Co1-yNiy)(2)-H-z system has been studied using both experimental techniques and ab initio calculations. The material was synthesised through high temperature synthesis and characterised using powder XRD. Hydrogen absorption and desorption was studied in-situ using synchrotron radiation. Maximal storage capacity increased when Co replaced Ni and substitution of Sc for Zr increased the equilibrium pressure. Density functional based calculations reproduce the experimental trends in terms of cell parameters both for the non-hydrogenated systems as well as for the hydrogenated systems, and helped to quantitatively understand the observed hydrogen uptake properties. 

  • 42.
    Ångström, Jonas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zlotea, Claudia
    Latroche, Michel
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hydrogen-sorption properties of Nb4M0.9Si1.1 (M = Co,Ni) hydrides2015In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 40, no 6, p. 2692-2697Article in journal (Refereed)
1 - 42 of 42
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf