Rationally Designed Ni–Ni₃S₂ Interfaces for Efficient Overall Water Electrolysis

Abstract

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/Ni 3 S 2 microsheets yields an electrode with high electrical conductivity and an abundance of accessible Ni 0 –Ni 3 S 2 interfaces as active sites for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In 1 m potassium hydroxide, Ni–Ni 3 S 2 /NF exhibits outstanding HER activity (an overpotential of 57 mV at a current density of 10 mA cm −2 ) and similarly impressive OER activity (a low overpotential of only 295 mV at a current density of 20 mA cm −2 ). A water electrolyzer constructed using Ni–Ni 3 S 2 /NF as the HER and OER electrodes exhibits a low cell voltage of only 1.57 V with no obvious performance loss over 30 h, outperforming devices based on expensive Pt/C and RuO 2 catalysts. To the best of the author's knowledge, Ni–Ni 3 S 2 /NF is one of the best non‐precious metal electrocatalysts reported to date for overall water splitting.