Oxygen Vacancies as Electronic Bridges to Reinforce Ru–TiO2 Metal-Support Interaction toward Efficient Electrocatalytic Acidic Hydrogen Evolution

Abstract

The development of hydrogen evolution reaction (HER) electrocatalysts that combine high activity, low cost, and long-term stability is crucial for advancing zero-carbon hydrogen energy technologies. Ru, with a 4d electronic structure similar to Pt and a comparatively lower cost, represents a highly promising alternative catalyst. However, its practical application is limited by challenges such as susceptibility to oxidation in acidic media and overly strong hydrogen adsorption. Here, we report a strong metal–support interaction (SMSI) strategy to construct Ru nanoparticles anchored on an oxygen-deficient TiO2-x support (Ru/TiO2-x), where oxygen vacancies function as electronic bridges to regulate interfacial electron transfer. In 0.5 M H2SO4 electrolyte, Ru/TiO2-x achieves a current density of 10 mA cm-2 at an ultralow overpotential of 11 mV and retains nearly unchanged activity over 350 h of continuous operation. Combined systematic characterizations and density functional theory calculations reveal that oxygen vacancies serve as electron donors, facilitating electron transfer from the TiO2-x support to Ru. This electron redistribution downshifts the d-band center of Ru, thereby optimizing the hydrogen adsorption energy. By clarifying the role of defect-engineered SMSI in modulating the electronic structure and catalytic behavior of Ru, this work provides a rational materials design strategy for developing highly efficient and stable Ru-based HER electrocatalysts.