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.