Electrocatalyst Performance in Acidic Aqueous and Solid Polymer Electrolytes

Abstract

Currently, aqueous electrolytes represent a model system for testing electrocatalyst performance. It is relatively easy to examine activity and stability of electrocatalysts performing simple half-cell electrochemical measurements in such electrolytes. On the other hand, modern electrochemical energy conversion devices such as fuel cells and water electrolysers use solid polymer electrolytes and ionomers in the catalyst layers, while water circulated in the system is deionized. An obvious question arises: "How good are aqueous electrolytes in representing operational conditions of real devices?” This presentation aims to address this question. While electrochemical activity of most catalysts is relatively similar in both environments, stability is not. Both, the extent of catalyst degradation and mechanisms responsible for stability depend on the electrolyte.1,2 Our recent work revealed that dissolution of iridium, as one of the degradation mechanisms, is significantly higher in aqueous acidic electrolytes.3 In order to understand this and other differences, several hybrid systems, i.e. repressing both aqueous and solid electrolytes, have been developed and tested. The main results of these experiments will be shown and discussed in this presentation. Acknowledgements: The project CREATE leading to these results has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 721065. Literature: 1 Cherevko, S. Current Opinion in Electrochemistry 8, 118-125 (2018). 2 Lafforgue, C. et al. ACS Catalysis 8, 1278-1286 (2018). 3 Geiger, S. et al. Nature Catalysis 1, 508-515 (2018).