Surface Reconstruction and Phase Transition on Vanadium–Cobalt–Iron Trimetal Nitrides to Form Active Oxyhydroxide for Enhanced Electrocatalytic Water Oxidation

The sluggish oxygen evolution reaction (OER) is a pivotal process for renewable energy technologies, such as water splitting. The discovery of efficient, durable, and earth‐abundant electrocatalysts for water oxidation is highly desirable. Here, a novel trimetallic nitride compound grown on nickel foam (CoVFeN @ NF) is demonstrated, which is an ultra‐highly active OER electrocatalyst that outperforms the benchmark catalyst, RuO2, and most of the state‐of‐the‐art 3D transition metals and their compounds. CoVFeN @ NF exhibits ultralow OER overpotentials of 212 and 264 mV at 10 and 100 mA cm−2 in 1 m KOH, respectively, together with a small Tafel slop of 34.8 mV dec−1. Structural characterization reveals that the excellent catalytic activity mainly originates from: 1) formation of oxyhydroxide species on the surface of the catalyst due to surface reconstruction and phase transition, 2) promoted oxygen evolution possibly activated by peroxo‐like (O22−) species through a combined lattice‐oxygen‐oxidation and adsorbate escape mechanism, 3) an optimized electronic structure and local coordination environment owing to the synergistic effect of the multimetal system, and 4) greatly accelerated electron transfer as a result of nitridation. This study provides a simple approach to rationally design cost‐efficient and highly catalytic multimetal compound systems as OER catalysts for electrochemical energy devices. This multimetal nitride system demonstrates greatly optimized electronic structure and local coordination environment, and enhanced the conductivity and active surface area as a catalyst in the oxygen evolution reaction (OER). The metal oxyhydroxide formed in the OER process due to the surface reconstruction and phase transition is an intrinsically active species for the OER. In addition, the promoted oxygen evolution is possibly activated by peroxo‐like (O22−) species.