Earth-abundant electrocatalysts for acidic oxygen evolution

Proton-exchange membrane water electrolysis is a promising technology for green hydrogen production, but its widespread commercialization is hindered by the high cost and scarcity of precious-metal-based catalysts for the oxygen evolution reaction (OER). Recent progress has been made in developing low-cost, earth-abundant electrocatalysts for the acidic OER, but little is known about degradation pathways. This makes the design of active and robust catalysts challenging. Here we review recent advances in the design of earth-abundant catalysts for the acidic OER, examining the degradation mechanisms from the device level to the catalyst electronic structure level, and highlighting the relevant characterization techniques. We discuss the thermodynamic and kinetic stability of the catalysts and present a quantitative comparative analysis of electrochemical data to evaluate different materials and design strategies for catalysts. We also examine the performance of the catalysts in proton-exchange membrane water electrolysers and conclude with a discussion of the key scientific challenges and future perspectives in the field.