Highly active and dual-function self-supported multiphase NiS–NiS2–Ni3S2/NF electrodes for overall water splitting

Abstract

The strategy of compatibly integrating cost-effective HER- and OER-active materials in a well-designed manner is expected to obtain bifunctional electrocatalysts for overall water splitting. We extend this strategy to a bifunctional self-supported electrode for water splitting to achieve a dynamic balance between the HER and OER through a fast, simple and economical fabrication process. The electrocatalytic activities of the self-supported multiphase NiS–NiS₂–Ni₃S₂/NF (m-NiS_x/NF) electrodes toward water splitting are obtained and optimized by modulating the quantity of sulfur powder during the reaction procedure. As a result, the self-supported m-NiS_x-0.5/NF electrode exhibits overpotentials of 143 mV and 137 mV to afford a current density of 20 mA cm⁻² for the OER and HER in 1.0 M KOH aqueous solution, respectively. Impressively, overall water splitting with 10 mA cm⁻² at a low voltage of 1.46 V is achieved using self-supported m-NiS_x-0.5/NF as both the anode and cathode electrodes, surpassing the performance of nearly all the recently reported nonprecious electrocatalysts for overall water splitting.