Single-Atom-Induced Adsorption Optimization of Adjacent Sites Boosted Oxygen Evolution Reaction

Noble metal-based single-atom catalysts play irreplaceable roles in the field of oxygen evolution reaction (OER). However, the tuning principles of noble metals for the physicochemical characteristics and the catalytic performance of substrates still remain elusive. Exploring the specific roles of noble metals at the atomic scale is therefore imperative to unravel the underlying interaction mechanism and develop high-performance OER electrocatalysts. This work was designed to disclose the correlation among structural heterogeneity, electronic structure, and catalytic performance by constructing well-defined atomic Ir on the substrate of Co3O4 via a thermal decomposition strategy. Isolated Ir was connected to six oxygen atoms to form the [IrO6] octahedron, which facilitated the formation of oxygen vacancies (Vo) to obtain Ir1@Vo–Co3O4. The synergy of Vo and atomic Ir upshifted the d-band center toward the Fermi level and yielded an active nanodomain with distinct electronic and geometric properties. The active nanodomain accelerated the electron transfer and strengthened the intermediates’ adsorption due to the optimized adsorption configuration, thereby dramatically boosting the catalytic activity. Moreover, the strong metal–support interaction stabilized both Co sites and Ir single atoms and suppressed the dynamic structural transformation of Co3O4 support during the OER process based on in situ Raman spectroscopy. The electrocatalytic activity of the resultant Ir0.33@Co3O4 is nearly 100-fold higher than that of IrO2 at the potential of 1.65 V versus the reversible hydrogen electrode in alkaline media at room temperature. When assembled as the cathode in the zinc–air battery, Ir1@Vo–Co3O4 demonstrated high power density and remarkable cycling durability.