Oxygen vacancies as electronic bridges to reinforce Ru-TiO₂ metal-support interactions toward efficient...

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 TiO_2-x support (Ru/TiO_2-x), where oxygen vacancies function as electronic bridges to regulate interfacial electron transfer. In 0.5 M H₂SO₄ electrolyte, Ru/TiO_2-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 characterization and density functional theory calculations reveal that oxygen vacancies serve as electron donors, facilitating electron transfer from the TiO_2-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 material design strategy for developing highly efficient and stable Ru-based HER electrocatalysts.