Regulating Ru electronic properties on cobalt oxide to boost water dissociation kinetics for efficient alkaline hydrogen evolution

Sluggish water dissociation kinetics consistently constrain the hydrogen evolution reaction (HER) in alkaline environments. Herein, we report a unique two-dimensional (2D) nanosheet electrocatalyst in which ruthenium (Ru) atoms are incorporated within a cobalt oxide heterojunction. Due to the electronic optimization of Ru sites engendered by the support effect of the cobalt oxide heterojunction, the Ru-Co 3 O 4 /CoO catalyst exhibits superior alkaline HER performance, characterized by an ultralow overpotential of 20 mV at 10 mA cm −2 and a notably small Tafel slope of 36 mV dec −1 , outperforming most previously reported noble-metal-based HER catalysts and the benchmark commercial Pt/C catalyst. Electrochemical measurements and electronic-structure analyses reveal efficient electron transfer from Ru to the Co₃O₄/CoO heterojunction, which promotes the formation of electron-deficient Ru sites and thereby result in exceptional HER activity. In situ Raman spectroscopy and theoretical calculations further demonstrate that modulation of Ru sites by the Co₃O₄/CoO heterojunction facilitates water dissociation, consequently accelerating the overall alkaline HER kinetics.