Metal oxides for the oxygen evolution reaction: tailoring electronic properties through structural modifications

The production and storage of green hydrogen can be effectively achieved through water splitting driven by renewable electricity. Of the two half-reactions involved in electrochemical water splitting, the oxygen evolution reaction is kinetically sluggish and typically serves as the rate-limiting step, thereby constraining the overall efficiency of the process. Consequently, the development of highly efficient electrocatalysts capable of promoting the oxygen evolution reaction at low overpotentials and high current densities remains a formidable scientific pursuit. Emerging studies on the reaction pathways and transient intermediates of the oxygen evolution reaction highlight that, beyond the overarching thermodynamic considerations, subtle aspects of the catalyst's structural, surface, and electronic characteristics play a decisive role in dictating catalytic performance. Factors such as the presence of accessible vacant sites adjacent to the catalytically active metal centers-introduced via intrinsic or extrinsic defect formation-along with the ease of oxidation of the active metal, the d-orbital electron configuration in octahedrally coordinated environments, and metal-ligand covalency, have all been identified as key descriptors governing oxygen evolution reaction activity. Our research group has been actively investigating pristine and doped transition metal spinel and perovskite oxides as potential oxygen evolution reaction electrocatalysts. This article outlines a systematic approach for rationally designing next-generation oxygen evolution catalysts based on critical electronic descriptors.