B‐Doping Tuning Oxygen Vacancies Facilitates Mechanism Transition in RuO ₂ for Oxygen Evolution at High Current Density

Water electrolysis is a key technology for green hydrogen production, and the development of efficient, pH‐universal oxygen evolution reaction (OER) electrocatalysts is crucial for enhancing the performance of water electrolyzers. Herein, a highly efficient OER electrocatalyst consisting of ultrafine RuO 2 nanoparticles supported on boron‐doped carbon (RuO 2 /BC) is developed, achieving exceptional activity and durability. B‐doping strategy modulates the electronic structure of the carbon support, inducing strong metal‐support electronic interactions with the RuO 2 particles. This promotes the formation of abundant oxygen vacancies on the RuO 2 surface and optimizes the electronic state of Ru sites, enabling a pH‐dependent switching of the OER mechanism. Electrochemically, in alkaline OER, the adsorbate evolution mechanism endows the catalyst with an overpotential at 1000 mA cm −2 (η 1000 ) of only 419 mV, while in acidic OER, the lattice oxygen mechanism leads to an η 1000 of 418 mV. Furthermore, the catalyst demonstrates exceptional durability, maintaining stable operation for over 200 h in a membrane electrode assembly device. This work provides a novel support‐engineering strategy for designing high‐performance and highly stable Ru‐based OER catalysts.