Acid-Stable Cu–O–Rh Group in a Densely Populated CuRh Single-Atom Alloy for Hydrogen Evolution Reaction

Developing acid-stable, nonprecious metal-based catalysts is crucial for the large-scale application of water electrolysis. Herein, we report an electrocatalyst with 17.4 wt % isolated Rh atoms embed in Cu nanoparticles (CuRh-1) with Cu–O–Rh bridge oxygen groups for the acidic hydrogen evolution reaction (HER), which exhibits activity with an overpotential of only 34 mV at a current density of 10 mA cm –2 and maintains stability over 100 h in 0.5 M H 2 SO 4, outperforming Rh/C and Pt/C. Ab-initio molecular dynamics (AIMD) and X-ray absorption spectroscopy (XAS) confirmed the formation of Cu–O–Rh bridge oxygen groups, which effectively stabilized the monatomic structure and enabled the synthesis of high-density CuRh single-atom alloys (CuRh-1 SAAs). DFT calculations and in situ Raman spectroscopy revealed the strong electrochemical stability of Cu–O–Rh bridge oxygen groups, underscoring their critical role in enhancing the HER stability. This insight into the formation mechanism provides a foundation for designing SAAs with a tunable loading and superior catalytic properties.