Low-iridium/ruthenium perovskite oxides: An emerging family of material platforms for oxygen evolution reaction in acid

Proton exchange membrane water electrolyzer (PEMWE) represents a highly promising technology for renewable hydrogen generation, urgently demanding low-cost, efficient, and robust anode oxygen evolution reaction (OER) electrocatalysts in acidic media. Over the past decade (mainly from 2016 onwards), low-Ir/Ru perovskite oxides have emerged as promising candidate materials for acidic OER electrocatalysis owing to their flexible element compositions and crystal structures, which can evidently reduce the noble-metal content and meanwhile significantly promote electrocatalytic performance. In this review, the current research progress in low-Ir/Ru perovskite oxides for acidic OER electrocatalysis is comprehensively summarized. Initially, we present a brief introduction to general issues relevant to acidic OER catalyzed by low-Ir/Ru perovskite oxides, such as the actual active species, OER mechanisms, inverse activity-stability relationship, and performance evaluation metrics. Subsequently, we present a thorough overview of various low-Ir/Ru perovskite oxides for acidic OER electrocatalysis, including single perovskites, double perovskites, triple perovskites, quadruple perovskites, Ruddlesden-Popper perovskites, and other complex perovskite-derived oxides, with emphasis on the intrinsic factors contributing to their exceptional performance and structure–property-performance correlation. Finally, remaining challenges and some promising insights to inspire future studies in this exciting field are provided.