Bulk-immiscible AgRh Alloy Nanoparticles as a Highly Active Electrocatalyst for the Hydrogen Evolution Reaction

Alloying metals can achieve enhanced kinetics for the hydrogen evolution reaction (HER), but most known HER alloy catalysts combine metals that are miscible in the bulk. Theoretical studies suggest that bulk-immiscible AgRh alloys will exhibit near-zero hydrogen binding energies, which is important for high-performing HER catalysts. Current routes to AgRh nanoparticles yield only small quantities or require specialized setups. Here, we establish a ligand-free, scalable synthesis of AgRh nanoparticles and demonstrate their catalytic viability for the HER under acidic conditions. AgRh nanoparticle electrodes exhibited low operating potentials with current densities of −10 and −100 mA/cm² at overpotentials of −17 and −32 mV, respectively. The electrodes were highly durable with very little change in overpotentials required to maintain hydrogen production for 24 h and after 400 successive cycles. These results establish bulk-immiscible AgRh alloys as promising non-Pt HER catalysts.