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Karimipour, M., Heydari-Bafrooei, E., Sanjari, M., Johansson, M. B. & Molaei, M. (2019). A glassy carbon electrode modified with TiO2(200)-rGO hybrid nanosheets for aptamer based impedimetric determination of the prostate specific antigen. Microchimica Acta, 186(1), Article ID 33.
Open this publication in new window or tab >>A glassy carbon electrode modified with TiO2(200)-rGO hybrid nanosheets for aptamer based impedimetric determination of the prostate specific antigen
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2019 (English)In: Microchimica Acta, ISSN 0026-3672, E-ISSN 1436-5073, Vol. 186, no 1, article id 33Article in journal (Refereed) Published
Abstract [en]

TiO2(200)-rGO hybrid nanosheets were synthesized starting from TiO2, rGO and NaOH solid powders via a scalable hydrothermal process. The weight ratio of TiO2-GO was found to be crucial on the crystal growth and biosensor properties of the final hybrid nanosheets. They were characterized by means of SEM, FESEM-EDX, XRD, XPS, Raman and FTIR spectroscopies in order to verify the formation of very thin TiO2 anatase nanosheets with an orientation of the anatase crystal structure towards the (200) plane. The free active sites of TiO2 structure and the large surface of the 2D graphene structure strongly facilitate charge transport confirmed by BET-BJH analyses. Compared to pure AuNPs, rGO and TiO2, the hybrid nanosheet modified electrode represents the most sensitive aptasensing platform for the determination of PSA. The detection was based on that the variation of electron transfer resistance (Rct) at the modified electrode surface in a solution containing 3.0mmolL(-1) [Fe(CN)(6)](3-/4-) as a redox probe and 0.1molL(-1) KCl as supporting electrolyte. The detection limit of the sensor is 1pgmL(-1), and the sensor can be operated up to 30days. It was applied to the analysis of PSA levels in spiked serum samples obtained from patients with prostate cancer. Data compare well with those obtained by an immunoradiometric assay.

Place, publisher, year, edition, pages
SPRINGER WIEN, 2019
Keywords
Work function, X-ray photoelectron spectroscopy, Effective surface area, Aptasensor, Electrochemical impedance spectroscopy, Voltammetry
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-372873 (URN)10.1007/s00604-018-3141-7 (DOI)000453796800007 ()30564911 (PubMedID)
Available from: 2019-01-10 Created: 2019-01-10 Last updated: 2019-01-10Bibliographically approved
Paulraj, A. R., Kiros, Y., Chamoun, M., Svengren, H., Noréus, D., Göthelid, M., . . . Johansson, M. B. (2019). Electrochemical Performance and in Operando Charge Efficiency Measurements of Cu/Sn-Doped Nano Iron Electrodes. Batteries, 5(1), Article ID 1.
Open this publication in new window or tab >>Electrochemical Performance and in Operando Charge Efficiency Measurements of Cu/Sn-Doped Nano Iron Electrodes
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2019 (English)In: Batteries, ISSN 2313-0105, Vol. 5, no 1, article id 1Article in journal (Refereed) Published
Abstract [en]

Fe-air or Ni-Fe cells can offer low-cost and large-scale sustainable energy storage. At present, they are limited by low coulombic efficiency, low active material use, and poor rate capability. To overcome these challenges, two types of nanostructured doped iron materials were investigated: (1) copper and tin doped iron (CuSn); and (2) tin doped iron (Sn). Single-wall carbon nanotube (SWCNT) was added to the electrode and LiOH to the electrolyte. In the 2 wt. % Cu + 2 wt. % Sn sample, the addition of SWCNT increased the discharge capacity from 430 to 475 mAh g-1, and charge efficiency increased from 83% to 93.5%. With the addition of both SWCNT and LiOH, the charge efficiency and discharge capacity improved to 91% and 603 mAh g-1, respectively. Meanwhile, the 4 wt. % Sn substituted sample performance is not on par with the 2 wt. % Cu + 2 wt. % Sn sample. The dopant elements (Cu and Sn) and additives (SWCNT and LiOH) have a major impact on the electrode performance. To understand the relation between hydrogen evolution and charge current density, we have used in operando charging measurements combined with mass spectrometry to quantify the evolved hydrogen. The electrodes that were subjected to prolonged overcharge upon hydrogen evolution failed rapidly. This insight could help in the development of better charging schemes for the iron electrodes.

Keywords
iron electrodes, Cu and Sn-doped iron, SWCNT and LiOH additives, charge efficiency, hydrogen evolution, GC-MS analysis
National Category
Materials Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-383086 (URN)10.3390/batteries5010001 (DOI)000464125800001 ()
Funder
Swedish Energy Agency, 39078-1
Available from: 2019-05-09 Created: 2019-05-09 Last updated: 2019-06-27Bibliographically approved
Öberg, V. A., Zhang, X., Johansson, M. B. & Johansson, E. M. J. (2018). Hot-Injection Synthesized Ag2S Quantum Dots with Broad Light Absorption and High Stability for Solar Cell Applications. CHEMNANOMAT, 4(12), 1223-1230
Open this publication in new window or tab >>Hot-Injection Synthesized Ag2S Quantum Dots with Broad Light Absorption and High Stability for Solar Cell Applications
2018 (English)In: CHEMNANOMAT, ISSN 2199-692X, Vol. 4, no 12, p. 1223-1230Article in journal (Refereed) Published
Abstract [en]

A hot-injection synthesis method was used to synthesize low-toxicity Ag2S colloidal quantum dots (CQDs) with strong and broad light absorption as an ultra-thin photo-absorber in CQD heterojunction solar cells. By using iodide and sulfur linkers it was possible to accomplish efficient charge carrier extraction, resulting in a high photocurrent due to the broad absorption spectrum. Transient photovoltage decay measurements were used to obtain information about trap states in the CQDs and the effect on the lifetime of the photoinduced carriers. The devices show very promising stability under constant long-term illumination and they are stable under ambient storage conditions with low losses to the performance over a period of over two months. These results show that Ag2S CQDs have high potential within solar cell applications, and point the direction for further improvements.

Keywords
energy conversion, hot-injection, quantum dots, silver sulfide, solar cells
National Category
Physical Chemistry Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-372703 (URN)10.1002/cnma.201800263 (DOI)000452048600005 ()
Funder
Swedish Energy AgencySwedish Research Council FormasSwedish Research CouncilÅForsk (Ångpanneföreningen's Foundation for Research and Development)
Available from: 2019-01-09 Created: 2019-01-09 Last updated: 2019-01-09Bibliographically approved
Zhang, X., Zhang, J., Phuyal, D., Du, J., Tian, L., Öberg, V. A., . . . Johansson, E. M. J. (2018). Inorganic CsPbI3 Perovskite Coating on PbS Quantum Dot for Highly Efficient and Stable Infrared Light Converting Solar Cells. Advanced Energy Materials, 8(6), Article ID 1702049.
Open this publication in new window or tab >>Inorganic CsPbI3 Perovskite Coating on PbS Quantum Dot for Highly Efficient and Stable Infrared Light Converting Solar Cells
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2018 (English)In: Advanced Energy Materials, ISSN 1614-6832, Vol. 8, no 6, article id 1702049Article in journal (Refereed) Published
Abstract [en]

Solution-processed colloidal quantum dot (CQD) solar cells harvesting the infrared part of the solar spectrum are especially interesting for future use in semitransparent windows or multilayer solar cells. To improve the device power conversion efficiency (PCE) and stability of the solar cells, surface passivation of the quantum dots is vital in the research of CQD solar cells. Herein, inorganic CsPbI3 perovskite (CsPbI3-P) coating on PbS CQDs with a low-temperature, solution-processed approach is reported. The PbS CQD solar cell with CsPbI3-P coating gives a high PCE of 10.5% and exhibits remarkable stability both under long-term constant illumination and storage under ambient conditions. Detailed characterization and analysis reveal improved passivation of the PbS CQDs with the CsPbI3-P coating, and the results suggest that the lattice coherence between CsPbI3-P and PbS results in epitaxial induced growth of the CsPbI3-P coating. The improved passivation significantly diminishes the sub-bandgap trap-state assisted recombination, leading to improved charge collection and therefore higher photovoltaic performance. This work therefore provides important insight to improve the CQD passivation by coating with an inorganic perovskite ligand for photovoltaics or other optoelectronic applications.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
charge recombination, inorganic perovskite, quantum dots, solar cells, surface passivation
National Category
Physical Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-348982 (URN)10.1002/aenm.201702049 (DOI)000426152400017 ()
Funder
Swedish Energy AgencySwedish Research CouncilSwedish Research Council Formas
Available from: 2018-04-26 Created: 2018-04-26 Last updated: 2018-10-26Bibliographically approved
Paulraj, A. R., Kiros, Y., Göthelid, M. & Johansson, M. B. (2018). NiFeOx as a Bifunctional Electrocatalyst for Oxygen Reduction (OR) and Evolution (OE) Reaction in Alkaline Media. CATALYSTS, 8(8), Article ID 328.
Open this publication in new window or tab >>NiFeOx as a Bifunctional Electrocatalyst for Oxygen Reduction (OR) and Evolution (OE) Reaction in Alkaline Media
2018 (English)In: CATALYSTS, ISSN 2073-4344, Vol. 8, no 8, article id 328Article in journal (Refereed) Published
Abstract [en]

This article reports the two-step synthesis of NiFeOx nanomaterials and their characterization and bifunctional electrocatalytic activity measurements in alkaline electrolyte for metal-air batteries. The samples were mostly in layered double hydroxide at the initial temperature, but upon heat treatment, they were converted to NiFe2O4 phases. The electrochemical behaviour of the different samples was studied by linear sweep voltammetry and cyclic voltammetry on the glassy carbon electrode. The OER catalyst activity was observed for low mass loadings (0.125 mg cm(-2)), whereas high catalyst loading exhibited the best performance on the ORR side. The sample heat-treated at 250 degrees C delivered the highest bi-functional oxygen evolution and reduction reaction activity (OER/ORR) thanks to its thin-holey nanosheet-like structure with higher nickel oxidation state at 250 degrees C. This work further helps to develop low-cost electrocatalyst development for metal-air batteries.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
Bi-functional catalyst, hydrothermal synthesis, OER/ORR, nickel ferrite, Ni FeLDH
National Category
Other Chemical Engineering Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-363948 (URN)10.3390/catal8080328 (DOI)000442517100033 ()
Funder
Swedish Energy Agency, 39078-1
Available from: 2018-10-22 Created: 2018-10-22 Last updated: 2018-10-22Bibliographically approved
Johansson, M. B., Xie, L., Thyr, J., Edvinsson, T., Göthelid, M., Niklasson, G. & Boschloo, G. (2018). Porous Fractals of MAPbI3 Perovskite: Characterization of Crystal Grain Formation by Irreversible Diffusion-Limited Aggregation. In: : . Paper presented at Materials Research Society Fall Meeting & Exhibit, November 25-30, 2018, Boston, Massachusetts, USA (pp. 1133). , Article ID ET05.14.07.
Open this publication in new window or tab >>Porous Fractals of MAPbI3 Perovskite: Characterization of Crystal Grain Formation by Irreversible Diffusion-Limited Aggregation
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2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Isopropanol solution based methylammonium lead triiodide (MAPbI3) is studied during the crystallization process. The crystal growth starts in an unstable suspension far from equilibrium by forming different dendritic patterns and terminates with aggregation of stable cubic crystalline grains into fractal clusters. Using transmission electron microscopy (TEM), the time evolution of a newly mixed suspension was studied over a period of two weeks at room temperature and a sequence of the morphological changes was observed. The crystallization process started with single dendritic growth exhibiting branches at 90 degrees angles to one another. After 4 hours, a multi-dendritic growth pattern and a transformation into small crystalline quantum dots were observed. After a week, clusters of crystal grains were formed into a fractal pattern and these patterns appear to be stable also during the second week. Electron and x-ray diffraction revealed the crystallinity of the quantum dots and the clusters of micrometer-sized crystals. Scanning transmission electron microscope (STEM) together with energy dispersive X-ray spectroscopy (EDS) showed that newly formed large grains, from a one hour old solution, displayed a core-shell structure with higher percentage of Pb atoms as compared to iodine at the surface. In the inner core of the grains the percentage of iodine was slightly higher. The electron diffraction (ED) scan over the newly formed grains revealed a polycrystalline surface whereas the inner part had a single crystal pattern. The same solution, now one-week-old, contained grains with only single crystal patterns in the ED scan and showed no core-shell character or polycrystalline surface. The measured percentage of iodine atoms compared to lead was 2:1 throughout the cross section, which is a quantitative value within the measurement. It can be concluded from these measurements that the suspension approaches higher crystallinity of the perovskite grains in an irreversible process, where the perovskite grains are insoluble in isopropanol. The perovskite material has also been characterized with scanning electron microscopy (SEM) and photoluminescence (PL) mapping where both techniques showed a very porous crystalline material. The PL mapping revealed two peaks at 730 and 760 nm for a thin film spin coated from a newly mixed solution, while a film deposited from a one week old solution showed three peaks, the last one at 830 nm. Because of the high crystallinity, it is suggested that all three peaks are due to band-to-band transitions and not due to localized states. These data will be analyzed further; however, the results contain information of the content of quantum dots versus larger crystals, as well as displaying emission intensity variations at different positions of the grains. The purpose with this project is to understand these phenomena of crystal growth. A new mesoporous perovskite material has been designed for optoelectronic purposes.

National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-369887 (URN)
Conference
Materials Research Society Fall Meeting & Exhibit, November 25-30, 2018, Boston, Massachusetts, USA
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2019-03-13Bibliographically approved
Zhu, H., Johansson, M. B. & Johansson, E. M. .. (2018). The Effect of Dopant-Free Hole-Transport Polymers on Charge Generation and Recombination in Cesium-Bismuth-Iodide Solar Cells. ChemSusChem, 11(6), 1114-1120
Open this publication in new window or tab >>The Effect of Dopant-Free Hole-Transport Polymers on Charge Generation and Recombination in Cesium-Bismuth-Iodide Solar Cells
2018 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 11, no 6, p. 1114-1120Article in journal (Refereed) Published
Abstract [en]

The photovoltaic characteristics of CsBi3I10-based solar cells with three dopant-free hole-conducting polymers are investigated. The effect on charge generation and charge recombination in the solar cells using the different polymers is studied and the results indicate that the choice of polymer strongly affects the device properties. Interestingly, for the solar cell with poly[[2,3-bis(3-octyloxyphenyl)-5,8-quinoxalinediyl]-2,5-thiophenediyl] (TQ1), the photon-to-current conversion spectrum is highly improved in the red wavelength region, suggesting that the polymer also contributes to the photocurrent generation in this case. This report provides a new direction for further optimization of Bi-halide solar cells by using dopant-free hole-transporting polymers and shows that the energy levels and the interaction between the Bi-halide and the conducting polymers are very important for solar cell performance.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
bismuth, cesium bismuth iodide, htm, polymer, solar cells
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-354358 (URN)10.1002/cssc.201702169 (DOI)000428315300015 ()29372625 (PubMedID)
Funder
Swedish Energy AgencySwedish Research CouncilSwedish Research Council Formas
Available from: 2018-06-28 Created: 2018-06-28 Last updated: 2019-09-04Bibliographically approved
Phuyal, D., Jain, S. M., Philippe, B., Johansson, M. B., Pazoki, M., Kullgren, J., . . . Rensmo, H. (2018). The electronic structure and band interface of cesium bismuth iodide on a titania heterostructure using hard X-ray spectroscopy. Journal of Materials Chemistry A, 6(20), 9498-9505
Open this publication in new window or tab >>The electronic structure and band interface of cesium bismuth iodide on a titania heterostructure using hard X-ray spectroscopy
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2018 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, no 20, p. 9498-9505Article in journal (Refereed) Published
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.

National Category
Materials Chemistry Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-357561 (URN)10.1039/c8ta00947c (DOI)000433427300020 ()
Funder
Swedish Research Council, 2014-6019Swedish Research Council, 2016-4524Swedish Energy Agency, P43549-1Swedish Foundation for Strategic Research , 15-0130Wallenberg Foundations, 2012.0031StandUp
Available from: 2018-08-20 Created: 2018-08-20 Last updated: 2019-02-19Bibliographically approved
Tian, L., Föhlinger, J., Pati, P. B., Zhang, Z.-B., Lin, J., Yang, W., . . . Tian, H. (2018). Ultrafast dye regeneration in a core-shell NiO-dye-TiO2 mesoporous film. Physical Chemistry, Chemical Physics - PCCP, 20(1), 36-40
Open this publication in new window or tab >>Ultrafast dye regeneration in a core-shell NiO-dye-TiO2 mesoporous film
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2018 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 1, p. 36-40Article in journal (Refereed) Published
Abstract [en]

In this study, a core-shell NiO-dye-TiO2 mesoporous film was fabricated for the first time, utilizing atomic layer deposition technique and a newly designed triphenylamine dye. The structure of the film was confirmed by SEM, TEM, and EDX. Excitation of the dye led to efficient and fast charge separation, by hole injection into NiO, followed by an unprecedentedly fast dye regeneration (t1/2 [less-than-or-equal] 500 fs) by electron transfer to TiO2. The resulting charge separated state showed a pronounced transient absorption spectrum caused by the Stark effect, and no significant decay was found within 1.9 ns. This indicates that charge recombination between NiO and TiO2 is much slower than that between the NiO and the reduced dye in the absence of the TiO2 layer (t1/2 [approximate] 100 ps).

Place, publisher, year, edition, pages
The Royal Society of Chemistry, 2018
National Category
Natural Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-335974 (URN)10.1039/C7CP07088H (DOI)000418374800002 ()
Funder
Knut and Alice Wallenberg Foundation, 2011.0067Swedish Energy Agency, 43599-1
Note

Correction in: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Volume: 20, Issue: 46, Pages: 29566-29566, DOI: 10.1039/c8cp91912g

Available from: 2017-12-11 Created: 2017-12-11 Last updated: 2019-01-17Bibliographically approved
Zhang, X., Aitola, K., Hägglund, C., Kaskela, A., Johansson, M. B., Sveinbjörnsson, K., . . . Johansson, E. M. J. (2017). Dry-Deposited Transparent Carbon Nanotube Film as Front Electrode in Colloidal Quantum Dot Solar Cells. ChemSusChem, 10(2), 434-441
Open this publication in new window or tab >>Dry-Deposited Transparent Carbon Nanotube Film as Front Electrode in Colloidal Quantum Dot Solar Cells
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2017 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 2, p. 434-441Article in journal (Refereed) Published
Abstract [en]

Single-walled carbon nanotubes (SWCNTs) show great potential as an alternative material for front electrodes in photovoltaic applications, especially for flexible devices. In this work, a press-transferred transparent SWCNT film was utilized as front electrode for colloidal quantum dot solar cells (CQDSCs). The solar cells were fabricated on both glass and flexible substrates, and maximum power conversion efficiencies of 5.5 and 5.6 %, respectively, were achieved, which corresponds to 90 and 92% of an indium-doped tin oxide (ITO)-based device (6.1 %). The SWCNTs are therefore a very good alternative to the ITO-based electrodes especially for flexible solar cells. The optical electric field distribution and optical losses within the devices were simulated theoretically and the results agree with the experimental results. With the optical simulations that were performed it may also be possible to enhance the photovoltaic performance of SWCNT-based solar cells even further by optimizing the device configuration or by using additional optical active layers, thus reducing light reflection of the device and increasing light absorption in the quantum dot layer.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2017
Keywords
carbon nanotubes, colloidal quantum dots, electrodes, optical loss, solar cells
National Category
Chemical Sciences Nano Technology
Identifiers
urn:nbn:se:uu:diva-319657 (URN)10.1002/cssc.201601254 (DOI)000394571900014 ()27873480 (PubMedID)
Funder
Göran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologySwedish Energy AgencySwedish Research Council FormasÅForsk (Ångpanneföreningen's Foundation for Research and Development)Swedish Research CouncilEU, European Research Council, 604472
Available from: 2017-04-07 Created: 2017-04-07 Last updated: 2017-11-29Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-2046-1229

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