Surface Hydroxyl Relay Promotes Acidic Water Oxidation

Ruthenium (Ru) is a promising iridium (Ir) alternative for proton exchange membrane water electrolysis (PEMWE), but Ru-based catalysts face an OER stability issue in acidic conditions. We addressed this using a hydroxyl relay strategy on RuO₂ surfaces via boron (B) doping. The three-coordinate B sites with empty p orbitals readily form coordination bonds with hydroxyl groups. These B sites relay *OH to neighboring Ru sites, facilitating the formation of the OOH intermediate, lowering the OER energy barrier, and preventing Ru overoxidation. Furthermore, the B dopants create a robust B-O-Ru local structure, which significantly stabilizes the catalyst framework. Consequently, the B-doped RuO₂ nanosheets (B-RuO₂ NS) show an ultralow overpotential (190 mV at 10 mA cm^-2) and exceptional stability (1600 h at 10 mA cm^-2, 200 h at 1 A cm^-2). This work demonstrates how targeted hydroxyl relay engineering can simultaneously enhance activity and stability, offering a viable pathway to develop high-performance and durable Ru catalysts for industrial PEMWE applications.