Electronic Structure Modulation of RuO₂ by TiO₂ Enriched with Oxygen Vacancies to Boost Acidic O₂ Evolution

RuO2 is the most efficient material reported so far for acidic oxygen evolution reaction (OER), yet suffering from insufficient stability in practical water-splitting operations. Targeting on this issue, herein we report an electronic structure modulating strategy by dispersing RuO2 over defective TiO2 enriched with oxygen vacancies (RuO2/D-TiO2). Synergetic (spectro-)electrochemistry and theoretical simulations reveal a continuous band structure at the interface between RuO2 and defective TiO2, as well as a lowered energetic barrier for *OOH formation, which are accountable for the largely enhanced acidic OER kinetics. As a result, the as-prepared RuO2/D-TiO2 catalyst exhibits a low overpotential of 180 mV at 10 mA cm–2, a low cell voltage of 1.84 V at 2 A cm–2, and a long lifetime above 100 h at 200 mA cm–2, providing hints for a more robust acidic OER catalyst design.