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 1mKOH, 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 (O-2(2-)) 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.