Advancing the Rigor and Reproducibility of Electrocatalyst Stability Benchmarking and Intrinsic Material Degradation Analysis for Water Oxidation

The stability of electrocatalysts is a concern for nearly all materials; degradation can occur via dissolution, leaching, sintering, amorphization, or reduction/oxidation processes. Extreme pH or large applied potentials often exacerbate these effects, but scant fundamental understanding of these processes exists due to complex structural and nanoscale effects in electrocatalysis. Instead, “catalyst stability” is often reported using broad electrode performance metrics, such as measured activity over time. To advance the fundamental understanding and comparison of catalyst materials, we propose that it is necessary to establish improved benchmarking metrics that reflect intrinsic material dynamics and stabilities of catalysts, supports, and substrates as a function of testing parameters, to complement existing metrics that primarily capture the performance of the complete electrode. We consider many degradation processes of lab-scale aqueous media systems, as well as membrane electrode assemblies and proton exchange membrane water electrolyzers, and consider the relatability between the two systems. Herein, we summarize various approaches to standardizing or benchmarking electrocatalyst performance, consider their strengths and weaknesses, and provide an outlook for advancing the rigor, specificity, and reproducibility of these techniques.