A highly active and durable NiMoCuCo catalyst with moderated hydroxide adsorption energy for efficient hydrogen evolution reaction†

Abstract

Nonprecious NiMo composites are promising hydrogen evolution reaction electrocatalysts due to their Pt-like catalytic surfaces. However, because of hydroxide adsorption in alkaline media, the oxidative elution of Mo deteriorates structural and catalytic stability. Herein, a Cu and Co incorporated NiMo composite (NiMoCuCo) is prepared as an active and durable hydrogen evolution reaction (HER) electrocatalyst by direct electrochemical deposition. The low electronegativities of Cu and Co effectively reduce the charge valence state of the metals and the zeta potential of the electrocatalysts, ameliorating surface electronegativity. NiMoCuCo shows a low overpotential of 53 mV at a current density of 10 mA cm⁻² and a slight overpotential increase of 0.01 mV h⁻¹ (1.8%) after a long-term stability test for 100 h at a current density of 100 mA cm⁻², outperforming NiMo and NiMoCu. Ex situ analyses demonstrate that NiMoCuCo exhibits a reduced charge valence state of Mo without significant degradation after the long-term stability test. Furthermore, Co in NiMoCuCo acts as the OH adsorption site on behalf of Mo, owing to the reduced surface electronegativity of Mo and strong OH affinity. This results in a balance between water dissociation and HER kinetics of NiMo composites, leading to excellent HER activity and stability.