A review of rare earth ruthenate pyrochlores as OER electrocatalysts in acidic media

Abstract

Ruthenate pyrochlores are highly tunable structures and promising OER electrocatalysts in both acidic and alkaline media. These structures provide a platform to balance activity, stability, and cost. This review critically examines the structural, electronic, and catalytic properties of rare-earth ruthenate pyrochlores, with a focus on how A- and B-site modifications and doping influence OER performance. We highlight the role of mixed-valence states, B–O covalency, and lattice distortions in enhancing catalytic activity, while also addressing the challenges of catalyst degradation and dissolution. Design strategies to further improve activity and stability are not clearly outlined in the literature, although the majority of studies incorporate acceptor doping to induce oxygen vacancies or mixed B-site valence. Furthermore, the review underscores the need for standardised electrochemical testing protocols. By consolidating recent advances and identifying structure–property relationships, this work provides a guideline for the rational design of pyrochlore OER electrocatalysts, as well as recommendations for how stability and activity should be evaluated.