Oxygen vacancies induced strong metal–support interactions of Ru@CoMoO ₄ –O _v for significantly enhanced oxygen evolution reaction performance in alkaline seawater electrolytes

Cobalt molybdate (CoMoO₄) is a potential material for the oxygen evolution reaction (OER) due to its stable crystal structure, strong redox capability, and abundant reserves. However, its poor electrical conductivity and high overpotential have limited its practical applications. In this study, the Ru@CoMoO₄-O_v/NF composite was prepared by loading Ru nanoparticles onto CoMoO₄ nanosheets and introducing oxygen vacancies (O_v). The interaction between Ru and CoMoO₄ promotes electron transfer from Ru to Co, and this process is further enhanced by oxygen vacancies, leading to the formation of high-valence Ruⁿ⁺. The high-valence Ruⁿ⁺ strengthens the adsorption of oxygen-containing intermediates, thereby facilitating O-H bond cleavage, reducing the energy barrier for H₂O decomposition, and improving OER performance. In 1 M KOH electrolyte, the catalyst exhibits an overpotential of only 249 mV at a current density of 10 mA cm^-2, with a Tafel slope of 74.8 mV dec^-1. When assembled into a two-electrode water-splitting system with FeP@CoP/NF, a current density of 10 mA cm^-2 is achieved at a voltage of merely 1.54 V. Moreover, the catalyst maintains excellent catalytic stability even in a complex alkaline seawater electrolyte. This study provides important insights into the modification mechanism of CoMoO₄-based catalysts.