Neighboring Site Synergies in Co-Defective Ru-Co Spinel Oxide toward Oxygen Evolution Reaction

As is well known that the oxygen evolution reaction (OER) is dominant to determine water splitting, regulating the electronic structure of the electrocatalyst has been demonstrated to be an effective strategy for improving OER activity. Herein, Ru- Co spinel oxides with abundant cobalt vacancies (VCo-RCO) are successfully developed as a highly efficient electrocatalyst for OER. Interestingly, the introduction of Ru can induce the formation of cobalt vacancies, which can modulate the electronic state of VCo- RCO, optimizing the location of the d-band center and generating neighboring Ru-Co synergies, thereby improving the OER catalytic activity. As a result, the VCo-RCO exhibits a small overpotential of 240 mV at 10 mA/cm2, which is more advanced than that of Co3O4, RCO without defect, and various RuO2 catalysts. The in situ Raman analysis and density functional theory calculations further confirm the neighboring Ru-Co synergies of VCo-RCO, and this mechanism can not only facilitate fast electron transfer between Ru and Co sites through the bridging OOH but also reduce the adsorption strength of OER intermediates, leading to a significant enhancement of OER catalytic activity.