MoO2 modulated electrocatalytic properties of Ni: investigate from hydrogen oxidation reaction to hydrogen evolution reaction

Exploring high-efficient non-noble metal hydrogen evolution reaction (HER) electrocatalysts is still a challenge for high purity hydrogen producing. The sluggish water dissociation kinetics (Volmer step) in alkaline electrolyte results in poorer HER activities than that in acid media. In this work, an efficient strategy to accelerate the Volmer step in alkaline media is proposed through the synergistic effect between metal and metal oxide. A hybrid catalyst composed of Ni/MoO2 was prepared by using a facile hydrothermal-reduction method. The metal nickel acts as the adsorption site for hydrogen, while MoO2 promotes the dissociation of water molecules and optimizes the Ni-H bond energy. In addition, the nanosheet structure is beneficial for exposing more active sites. Electrochemical test reveals that the Ni/MoO2 catalyst exhibits outstanding HER performance with a small overpotential of 40 mV to deliver the current density of 10 mA cm(-2) as well as excellent stability. Hydrogen oxidation reaction (HOR) experiment was performed to study the mechanistic insights into the activity enhancement. (C) 2019 Elsevier Ltd. All rights reserved.