Oxygen-Incorporated NiMoP2 Nanowire Arrays for Enhanced Hydrogen Evolution Activity in Alkaline Solution

Abstract

Catalytic water splitting for commercial hydrogen production demands efficient and robust earth-abundant catalysts. However, sluggish kinetics of water dissociation in alkaline electrolyte impedes the formation of reactive intermediates by discharge of water. Here, oxygen-incorporated NiMoP2 nanowire arrays are engineered on Ni foam substrate (denoted as O-NiMoP2/Ni) by controllable partial phosphorization of metal oxide precursors to boost HER activity under alkaline environment. The incorporation of oxygen can significantly modify the electronic structure of NiMoP2 and optimize both HER Gibbs free-energy change (ΔGH*) and water adsorption energy change (ΔGH2O*). Results demonstrate that the O-NiMoP2/Ni nanowire arrays require quite low HER overpotentials of 31 and 134 mV to drive the geometrical catalytic current densities of 10 and 100 mA cm–2, respectively. The activity and stability in 1 M KOH are also superior to those of the state-of-the-art transition-metal phosphides (TMPs).