Accelerating hydrogen evolution at neutral pH by destabilization of water with a conducting oxophilic metal oxide

Abstract

Electrolysis in neutral media is vital for cost-efficient hydrogen production utilizing vast resources like wastewater and seawater. However, the required high overpotential remains an enormous obstacle, which is due to the sluggish water dissociation Volmer step along with the subsequent proton recombination step. Herein, choosing strongly oxophilic and metallic vanadium sesquioxide (V₂O₃) as the water dissociation center, we present the synthesis of self-supporting Ni₄Mo–V₂O₃ nanosheets via topotactic transformation of oxometallate intercalated layered double hydroxide (LDH). Benefiting from their good electrical conductivity, large electrochemical surface area, exposed active sites and abundant heterogeneous interfaces, Ni₄Mo–V₂O₃ nanosheets exhibit an extremely low overpotential of 39.3 mV at 10 mA cm⁻² and a Tafel slope of 65.7 mV dec⁻¹ for the hydrogen evolution reaction (HER) at neutral pH. Density functional theory calculations confirm that V₂O₃ on Ni₄Mo alloy enhances water adsorption and reduces the energy barriers for water dissociation, as well as the subsequent H₂ generation, thus achieving superior HER performance in neutral electrolyte.