Accelerated alkaline hydrogen evolution on M(OH)x/M-MoPOx (M = Ni, Co, Fe, Mn) electrocatalysts by coupling water dissociation and hydrogen ad-desorption steps

Abstract

Developing efficient and cheap electrocatalysts for the alkaline hydrogen evolution reaction is still a big challenge due to the sluggish water dissociation kinetics as well as poor M–H_ad energetics. Herein, hydroxide modification and element incorporation have been demonstrated to realize a synergistic modulation on a new class of M(OH)_x/M-MoPO_x catalysts for accelerating water dissociation and hydrogen ad-desorption steps in the HER. Theoretical and experimental results disclosed that in situ modification with hydroxide endowed M(OH)_x/M-MoPO_x with a strong ability to dissociate water, and meanwhile, oxygen incorporation effectively optimized the M–H_ad energetics of the NiMoP catalyst. Moreover, the interaction between M(OH)_x and M-MoPO_x components in M(OH)_x/M-MoPO_x further enhances their ability to catalyze the two elementary steps in alkaline hydrogen evolution, providing a wide avenue for efficiently catalyzing hydrogen evolution. In general, the optimized Ni(OH)₂/NiMoPO_x catalyst exhibits excellent alkaline HER activity and durability, superior to the state-of-the-art Pt/C catalyst when the overpotential exceeds 65 mV.