Oxygen vacancies as electronic bridges to reinforce Ru–TiO2 metal–support interactions 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 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.