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 H₂ 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.