Constructing interfacial structure of Mo5N6/Ni3N/Ni/NF for efficient and stable electrocatalytic hydrogen evolution under alkaline conditions

Abstract

Alkaline water splitting is an economical approach for producing hydrogen. However, due to the sluggish kinetics of alkaline water dissociation, the activity and stability of the catalyst remain the critical and challenging aspects of this process. Here, we prepared a Ni foam (NF) based, self-supporting catalyst with a porous hierarchical structure: Mo₅N₆/Ni₃N/Ni/NF, which shows good catalytic activity and stability towards the hydrogen evolution reaction (HER). The catalyst has a porous hierarchical structure, in which the interface between Mo₅N₆ and Ni₃N promotes the adsorption and dissociation of water, whereas Mo₅N₆ improves the stability of the catalyst in an alkaline medium and also facilitates the desired desorption of hydrogen. As a result, the overpotentials required for Mo₅N₆/Ni₃N/Ni/NF to achieve current densities of −10 mA cm⁻² and −100 mA cm⁻² were only 27 and 83 mV, respectively. During 100 h of chronopotentiometry measurements, the catalyst performance hardly attenuates at a current density of −100 mA cm⁻². With such characteristics, the self-supporting catalyst with layered structure provides a reference for the structural design of subsequent HER electrocatalysts and provides new insights into the understanding of nitrogen-rich metal nitride-based catalysts.