Doping Ti into RuO₂ to Accelerate Bridged-Oxygen-Assisted Deprotonation for Acidic Oxygen Evolution Reaction

The development of efficient and durable electrocatalysts for the acidic oxygen evolution reaction (OER) is essential for advancing renewable hydrogen energy technology. However, the slow deprotonation kinetics of oxo-intermediates, involving the four proton-coupled electron steps, hinder the acidic OER progress. Herein, a RuTiO_x solid solution electrocatalyst is investigated, which features bridged oxygen (O_bri) sites that act as proton acceptors, accelerating the deprotonation of oxo-intermediates. Electrochemical tests, infrared spectroscopy, and density functional theory results reveal that the moderate proton adsorption energy on O_bri sites facilitates fast deprotonation kinetics through the adsorbate evolution mechanism. This process effectively prevents the over-oxidation and deactivation of Ru sites caused by the lattice oxygen mechanism. Consequently, RuTiO_x shows a low overpotential of 198 mV at 10 mA cm^-2 _geo and performance exceeding 1400 h at 50 mA cm^-2 _geo with negligible deactivation. These insights into the OER mechanism and the structure-function relationship are crucial for the advancement of catalytic systems.