Self-optimizing Cobalt Tungsten Oxide Electrocatalysts toward Enhanced Oxygen Evolution in Alkaline Media

Self-optimizing mixed metal oxides are a novel class of electrocatalysts for the advanced oxygen evolution reaction (OER). Here, we report the self-assembled cobalt and tungsten oxide nanostructures on the lab-synthesized copper oxide substrate via a one-step deposition approach. The resulting composite demonstrates remarkable self-optimization, achieving significantly reduced overpotentials and enhanced current densities. Mechanistic investigations reveal the origins of the boosted OER performance, highlighting substantial enhancements in OER kinetics, the electrocatalytically active surface area, surface wettability, and electrical conductivity. Interfacial restructuring of the electrocatalyst under operating conditions indicates the in situ formation of oxidized cobalt species as true active sites. Complementary density functional theory (DFT) analysis demonstrates the formation of *OOH as the rate-determining step of OER, and elucidates the self-activation mechanism originating from the adaptation of adsorbed oxygen intermediates binding site from tungsten to cobalt. Our study provides a fundamental understanding of the self-optimization mechanism and advances the knowledge-driven design of efficient water-splitting electrocatalysts.