Hydrogen spillover in Ru/Cr2O3 enhances alkaline hydrogen evolution reaction activity

Abstract

Hydrogen energy, as a pivotal medium for large-scale deployment of renewable energy, demands efficient production pathways, which hinge critically on breakthroughs in the activity and stability of alkaline hydrogen evolution reaction (HER) catalysts. Addressing the sluggish water dissociation kinetics and constrained hydrogen spillover pathways associated with Ru-based catalysts in alkaline media, we propose a multi-interface engineered Ru/Cr₂O₃/Cu composite catalyst. In this system, ultrafine Ru nanoparticles are supported on a Cr₂O₃ scaffold embedded with highly conductive Cu particles. The intimate Cu–Cr₂O₃ interfaces form an integrated electron transport network, while protons generated from water dissociation on Cr₂O₃ surfaces are efficiently transferred to Ru active sites via interfacial hydrogen spillover. Simultaneously, the Ru/Cr₂O₃ heterojunction modulates the hydrogen adsorption strength on Ru, synergistically accelerating both the Volmer and Tafel steps. Experimental results demonstrate that this catalyst achieves a current density of 10 mA cm⁻² at an ultralow overpotential of only 18 mV in 1.0 M KOH, while maintaining stable operation at 100 mA cm⁻² and 200 mA cm⁻² for over 100 h. This work demonstrates an effective strategy for interfacial engineering in high-performance alkaline HER catalysts, and provides insights into the coupling of conductivity modulation and hydrogen spillover at the atomic scale.