Abstract
ABSTRACT
The oxygen evolution reaction (OER) is a kinetically demanding anodic process in water electrolysis and related electrochemical energy‐conversion systems. Its multistep proton‐coupled electron‐transfer kinetics and catalyst degradation under strongly oxidizing conditions limit overall efficiency and durability. High‐entropy oxides (HEOs), which combine multicomponent configurational disorder, lattice distortion, broad distributions of local coordination environments, and element‐specific electronic interactions, have emerged as a versatile platform for OER catalyst design. This review summarizes the definitions and physicochemical characteristics of HEOs, OER reaction pathways, theoretical and data‐driven methods, synthesis strategies, representative crystal structures, and recent progress in acidic OER and proton‐exchange‐membrane water electrolysis (PEMWE). Particular attention is given to rutile‐type Ir/Ru‐based HEOs, including their phase formation, local electronic‐structure regulation, degradation behavior, and device‐level validation. Current challenges in composition‐space exploration, operando mechanism identification, long‐term stability, noble‐metal utilization, reproducible scale‐up, and standardized device testing are discussed, together with directions for future research.