Key Role of Bridge Adsorbed Hydrogen Intermediate on Pt–Ru Pair for Efficient Acidic Hydrogen Production

Abstract Atop and multiple adsorbed hydrogen are considered as key intermediates on Pt‐group metal for acidic hydrogen evolution reaction (HER), yet the role of bridge hydrogen intermediate ( ^* H _bridge ) is consistently overlooked experimentally. Herein, a Pt atomic chain modified fcc ‐Ru nanocrystal (Pt–Ru( fcc )) is developed with a co‐crystalline structure, featuring ^* H _bridge intermediate bonded on the Pt–Ru pair site. Electrons leap from the pair site to ^* H _bridge facilitate hydrogen desorption, thus accelerating the Tafel kinetics and ensuring outstanding electrocatalytic performance, with a low overpotential (4.0 mV at 10 mA cm ⁻² ) and high turnover frequency (56.4 H ₂ s ⁻¹ at 50 mV). Notably, the proton exchange membrane water electrolyzer PEMWE with ultra‐low loading of 10 ug _Pt cm ⁻² shows excellent activity (1.61 V at 1.0 A cm ⁻² ) and low average degradation rate (4.0 µV h ⁻¹ over 1000 h), significantly outperforming the benchmark Pt/C. Furthermore, the PEMWE‐based 80 µm Gore membrane under identical operating conditions requires only 1.54 and 1.58 V to achieve 1.0 and 1.5 A cm ⁻² . This finding highlights the key role of ^* H _bridge at the Pt–Ru interface in obtaining high HER intrinsic activity and underscores the transformative potential in designing next‐generation bimetallic catalysts for clean hydrogen energy.