Bidirectional Hydrogen Spillover Enables High Activity Catalysts for Rechargeable Hydrogen Batteries

Abstract Rechargeable hydrogen batteries exhibit superior electrochemical activity for hydrogen evolution and oxidation reactions (HER/HOR) in acidic media compared to alkaline counterparts, making them promising for large‐scale energy storage. However, the development of efficient electrocatalysts for both HER and HOR in acidic media remains challenging, as conventional platinum‐based catalysts face intrinsic limitations in simultaneously achieving high activity and long‐term stability under harsh operating conditions. Herein, we introduce a bidirectional hydrogen spillover strategy to enable synergistic bifunctional HER/HOR catalysts for hydrogen batteries. We demonstrate a Ru–WO 3 catalyst grown on Cu foam (Ru–WO 3 @CF), where the interaction between Ru and WO 3 enables dynamic shuttling of adsorbed hydrogen species under alternating potentials. The Ru–WO 3 @CF electrode demonstrates exceptional HER/HOR bifunctionality in acidic media (0.5 M H 2 SO 4 ), achieving an ultralow HER overpotential of 17 mV at 10 mA cm −2 and an HOR current density of 21.5 mA cm −2 at 50 mV — both significantly outperforming commercial Pt/C benchmarks. The hydrogen battery fabricated with Ru–WO 3 @CF demonstrates exceptional performance across a wide range of temperatures. This work aims to explore the feasibility of bidirectional hydrogen spillover in enhancing the bifunctional catalytic activities toward HER/HOR, providing new insights for high‐performance hydrogen batteries.