Stable hydrogen evolution reaction at high current densities via designing the Ni single atoms and Ru nanoparticles linked by carbon bridges.

Continuous and effective hydrogen evolution under high current densities remains a challenge for water electrolysis owing to the rapid performance degradation under continuous large-current operation. In this study, theoretical calculations, operando Raman spectroscopy, and CO stripping experiments confirm that Ru nanocrystals have a high resistance against deactivation because of the synergistic adsorption of OH intermediates (OH) on the Ru and single atoms. Based on this conceptual model, we design the Ni single atoms modifying ultra-small Ru nanoparticle with defect carbon bridging structure (UP-RuNi/C) via a unique unipolar pulse electrodeposition (UPED) strategy. As a result, the UP-RuNi/C is found capable of running steadily for 100 h at 3 A cm, and shows a low overpotential of 9 mV at a current density of 10 mA cm under alkaline conditions. Moreover, the UP-RuNi/C allows an anion exchange membrane (AEM) electrolyzer to operate stably at 1.95 V for 250 h at 1 A cm.