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

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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.