A Novel Evaluation Method of Powder Electrocatalyst for Gas Evolution Reaction (Supporting Information)

The evaluation of the powder catalyst activity is essential for the development of high-performance electrocatalysts for water electrolysis. However, the gas generated therein interferes with the accurate measurement by covering the catalyst surface. In this study, we have developed a new evaluation method for a powder oxide electrocatalyst using an alkaline electrolyte. This measurement and analysis method can obtain the intrinsic catalyst activity with no influence from the generation of bubbles. To establish this method, the electrolyzer for evaluation adopts the interdigit flow field for the forced-flow method, and the two methods, namely time zero analysis and flow rate infinitization analysis, were demonstrated by the extrapolation of the measurement data. As a result, the combination of forced-flow method and time-zero analysis is the best evaluation method for the determination of kinetic current at time zero as the equivalent of the no-generation gas condition.