Rationally Designed Ni-Ni3S2 Interfaces for Efficient Overall Water Electrolysis

High-performance water-splitting electrocatalysts are needed by the energy sector for sustainable hydrogen production. Herein, it is demonstrated that the surface decoration of a nickel foam (NF) with porous Ni/Ni3S2 microsheets yields an electrode with high electrical conductivity and an abundance of accessible Ni-0-Ni3S2 interfaces as active sites for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In 1m potassium hydroxide, Ni-Ni3S2/NF exhibits outstanding HER activity (an overpotential of 57mV at a current density of 10mAcm(-2)) and similarly impressive OER activity (a low overpotential of only 295mV at a current density of 20mAcm(-2)). A water electrolyzer constructed using Ni-Ni3S2/NF as the HER and OER electrodes exhibits a low cell voltage of only 1.57V with no obvious performance loss over 30h, outperforming devices based on expensive Pt/C and RuO2 catalysts. To the best of the author's knowledge, Ni-Ni3S2/NF is one of the best non-precious metal electrocatalysts reported to date for overall water splitting.