A Novel Evaluation Method of Powder Electrocatalyst for Gas Evolution Reaction

Abstract

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.

Improvement of Time-zero Analysis Method in Activity Evaluation of Powder Electrocatalyst for Gas Evolution Reaction

“…We reported the forced-flow method and the time-zero analysis as a new activity evaluation method for gas-evolution powder catalysts using LNO as an example, 11 in order to eliminate the influence of the catalyst-enveloping by generated gas bubbles and to evaluate the intrinsic activity of the catalyst. The forced flow method is a catalyst setup method in which the catalyst layer is placed in the rib of an interdigit flow field, and the electrolyte is forced to flow through the catalyst layer to eliminate the created bubbles.…”

“…In former time-zero analysis, 11 time range for linear approximation in t 1/2 ¹ i ¹1 plot was fixed between 5¸d l and 10 ms and the line was extrapolated. This corresponds approximately to the first half of the linear region.…”