Progress on the mechanisms of Ru-based electrocatalysts for the oxygen evolution reaction in acidic media

Water electrolysis using proton-exchange membranes is one of the most promising technologies for carbon-neutral and sustainable energy production. Generally, the overall efficiency of water splitting is limited by the oxygen evolution reaction (OER). Nevertheless, a trade-off between activity and stability exists for most electrocatalytic materials in strong acids and oxidizing media, and the development of efficient and stable catalytic materials has been an important focus of research. In this view, gaining in-depth insights into the OER system, particularly the interactions between reaction intermediates and active sites, is significantly important. To this end, this review introduces the fundamentals of the OER over Ru-based materials, including the conventional adsorbate evolution mechanism, lattice oxygen oxidation mechanism, and oxide path mechanism. Moreover, the up-to-date progress of representative modifications for improving OER performance is further discussed with reference to specific mechanisms, such as tuning of geometric, electronic structures, incorporation of proton acceptors, and optimization of metal-oxygen covalency. Finally, some valuable insights into the challenges and opportunities for OER electrocatalysts are provided with the aim to promote the development of next-generation catalysts with high activity and excellent stability.