Optimized immobilization of ZnO:Co electrocatalysts realizes 5% efficiency in photo-assisted splitting of water
| Autor: | Matthias Driess, Anahita Azarpira, Bernd Stannowski, Thomas Schedel-Niedrig, Johannes Pfrommer, Michael Lublow, Christian Höhn, Katarzyna Olech |
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| Rok vydání: | 2016 |
| Předmět: |
Materials science
Renewable Energy Sustainability and the Environment Inorganic chemistry Oxygen evolution 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Tin oxide 01 natural sciences Nanocrystalline material 0104 chemical sciences law.invention Electrophoretic deposition chemistry.chemical_compound chemistry law ddc:540 Solar cell Deposition (phase transition) ddc:530 General Materials Science 0210 nano-technology Acetonitrile Porosity |
| Zdroj: | Journal of Materials Chemistry A. 4:3082-3090 |
| ISSN: | 2050-7496 2050-7488 |
| DOI: | 10.1039/c5ta07329d |
| Popis: | Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich. This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. Correction: There is an error in Fig. 8 of the manuscript. The correct Fig. 8 is shown in the additional file. To cite the Correction refer to DOI:10.1039/c6ta90030e. Organic solvents with varied electrophoretic mobility have been employed for deposition of nanocrystalline ZnO: Co particles onto fluorinated tin oxide supports. Evaluation of the electrochemical activity for the oxygen evolution reaction proves a clear solvent-dependence with highest activity upon deposition from acetonitrile and lowest activity upon deposition from ethanol. Analysis of the resulting layer thickness and density attributes the improved electrochemical activity of acetonitrile-prepared samples to larger film thicknesses with lower film densities, i.e. to films with higher porosity. The findings suggest that the ZnO: Co films represent an initially nanocrystalline system where the catalytic activity is predominantly confined to a thin surface region rather than to comprise the entire volume. Closer inspection of this surface region proves successive in operando transformation of the nanocrystalline to an amorphous phase during evolution of oxygen. Furthermore, less active but highly transparent ZnO: Co phases, prepared from ethanol-containing suspensions, can be successfully employed in a stacking configuration with a low-cost triple-junction solar cell. Thereby, a solar-to-hydrogen efficiency of 5.0% in splitting of water at pH 14 could be realized. In contrast, highly light-absorbing acetonitrile/acetone-prepared samples limit the efficiency to about 1%, demonstrating thus the decisive influence of the used organic solvent upon electrophoretic deposition. Stability investigations over several days finally prove that the modular architecture, applied here, represents an attractive approach for coupling of highly active electrocatalysts with efficient photovoltaic devices. |
| Databáze: | OpenAIRE |
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