Influence of temperature and illumination intensity on the stability of LaTiO 2 N based photoanodes Julian Hörndl 1 , Franky Bedoya 2 , Sophia Haussener 2 , Simone Pokrant 1 1 Department of Chemistry and Physics of Materials, Paris Lodron University Salzburg, Jakob- Haringer-Str. 2A, 5020 Salzburg, Austria, 2 Laboratory of Renewable Energy Science and Engineering, Ecole Polytechnique Federalede Lausanne, 1015 Lausanne, Switzerland The direct conversion of solar energy into chemical energy in the form of solar fuels (e.g. green hydrogen), has the potential to contribute significantly to cover our energy needs [1,2] . Due to its comparably simple setup photoelectrochemical (PEC) water splitting shows promise as a cost-effective method for producing green hydrogen in the future [3,4] . A PEC system consists of two spatially separate electrodes connected via an ohmic contact, with the water oxidation taking place on the anode side and the hydrogen reduction on the cathode side of the cell [5] . While there have been significant advancements regarding the efficiency of PEC systems, their stability remains a major challenge [2,4,6] . Based on several technoeconomic studies an operation time of at least two years without major degradation is required for an economic application of PEC devices [1,3] . However, running stability tests over several years is very time consuming and thus hardly feasible. Therefore, methods for the evaluation of the long-term stability of PEC systems at shorter time scales need to be developed. As potential approach to simulate accelerated aging could be the use of high flux conditions (>100 kW m-²) [7] . However, before implementing such a method, first the impact of high flux conditions on the degradation behaviour of photoanodes must be investigated. Since the use of high flux conditions might also lead to an increase of the cell temperature, its influence on the degradation must be considered as well [8, 9] . In this study the influence of illumination intensity and electrolyte temperature on the performance and degradation of oxynitride electrodes, focusing on the showcase of LaTiO 2 N (LTON) particle-based photoanodes, was investigated. The LTON was synthesized via solid state synthesis followed by thermal ammonolysis. The photoanodes were prepared by electrophoretic deposition followed by TiCl 4 necking and cocatalyst application via dip coating. The performance and degradation of the LTON based photoanodes at different electrolyte temperatures and illumination intensities were investigated using chronoamperometry in combination with linear scan voltammetry before and after multiple hours of exposure. ICP-MS was used to detect potential dissolution of cations into the electrolyte. The photoanodes were investigated post-mortem with respect to compositional, morphological and optical changes using STEM-EDX, SEM and UV-Vis-Spectroscopy. References 1. Segev, G., et al., Journal of Physics D: Applied Physics, 2022. 55(32): p. 2. Vilanova, A., et al., Chem Soc Rev, 2024. 53(5): p. 2388-2434.
3. Schneidewind, J., Advanced Energy Materials, 2022. 12(18): p. 2200342. 4. Vanka, S., et al., . Frontiers in Energy Research, 2022. 10: p 840140. 5. Alley, O.J., et al., Frontiers in Energy Research, 2022. 10: p 884364. 6. Pirrone, N., F. Bella, and S. Hernández, Green Chemistry, 2022. 24(14): p. 5379-5402. 7. Holmes-Gentle, I., et al., Journal of Materials Chemistry A, 2023. 11(44): p. 23895-23908 8. Werner, V., et al., RSC Sustainability, 2024. 2: p. 1738-1752 9. Bedoya-Lora, F.E., et al., Electrochimica Acta, 2023. 462: p. 142703.
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