Synergistic Oxygen Vacancy and Ru–N Coordination in RuO ₂ @NCC for Enhanced Acidic Oxygen Evolution Reaction

ABSTRACT Developing efficient and durable electrocatalysts for acidic oxygen evolution reaction (OER) is pivotal for advancing proton exchange membrane water electrolysis (PEMWEs), yet balancing activity and stability remains a formidable challenge. Herein, we propose a dual‐engineering strategy to stabilize Ru‐based catalysts by synergizing the oxygen vacancy site‐synergized mechanism‐lattice oxygen mechanism (OVSM‐LOM) with Ru–N bond stabilization. The engineered RuO 2 @NCC catalyst exhibits exceptional OER performance in 0.5 M H 2 SO 4 , achieving an ultralow overpotential of 215 mV at 10 mA cm –2 and prolonged stability for over 327 h. The catalyst delivers 300 h of continuous operation at 1 A cm –2 , with a negligible degradation rate of only 0.067 mV h –1 , further demonstrating its potential for practical application. Oxygen vacancies unlock the OVSM‐LOM pathway, bypassing the sluggish adsorbate evolution mechanism (AEM) and accelerating reaction kinetics, while the Ru–N bonds suppress Ru dissolution by anchoring low‐valent Ru centers. Quasi‐in situ X‐ray photoelectron spectroscopy (XPS), X‐ray absorption spectroscopy (XAS), and isotopic labeling experiments confirm the lattice oxygen participation with *O formation as the rate‐determining step. The Ru–N bonds reinforce the structural integrity by stabilizing low‐valent Ru centers and inhibiting overoxidation. Theoretical calculations further verify that the synergistic interaction between O Vs and Ru–O(N) active sites optimizes the Ru d‐band center and stabilizes intermediates, while Ru–N coordination enhances structural integrity. This study establishes a novel paradigm for designing robust acidic OER catalysts through defect and coordination engineering, bridging the gap between activity and stability for sustainable energy technologies.