Dynamic Reconstruction of Vanadium Oxide Species Modified Ruthenium‐Cerium Catalysts: Electron Bridge and Hydrogen‐Bond Network Disruption for Efficient Acidic Hydrogen Evolution

ABSTRACT Developing efficient electrocatalysts for the hydrogen evolution reaction (HER) in acidic media is critical for proton exchange membrane water electrolyzers (PEMWEs). Herein, we report a Ru–CeVO X catalyst with oxygen vacancies and surface vanadium oxide species. The optimized Ru–CeVO X exhibits excellent HER activity in 0.5 M H 2 SO 4 , achieving overpotentials of 35.9 mV at 10 mA cm −2 and 193.6 mV at 1000 mA cm −2 , outperforming commercial Pt/C. In a PEMWE device, it delivers 1 A cm −2 at 1.80 V and maintains stability for over 400 h at 500 mA cm −2 . Time‐resolved ICP‐OES reveals in situ reconstruction, during which Ru 0 redeposits to form a dynamically stable, Ru‐rich active surface. Vanadium plays a dual critical role. The vanadium oxide species anchor onto the CeO 2 surface, constructing a Ru–O–Ce–O–V electron bridge that withdraws electrons from Ru, stabilizing Ru 0 and optimizing its d‐band center for near‐ideal H* adsorption. vanadium oxide species actively disrupt the interfacial hydrogen‐bonding network, reducing strongly bound water and increasing free water molecules. This disruption facilitates H* recombination on adjacent Ru sites, accelerating the Tafel step which is the rate‐determining step of HER on Ru–CeVO X . Thus, vanadium‐induced reconstruction, combining electron bridging and hydrogen‐bond disruption, offers a powerful strategy for designing high‐performance acidic HER catalysts.