Enhanced electrocatalytic performance of CuxNi1-xS Nanoflakes for overall water splitting

Abstract

For long-term energy storage and conversion, the design of commercial and high-performance catalysts for bifunctional electrocatalytic water splitting is critical. We report the efficient method to prepare Cu_xNi_1-xS Nanoflakes (NFs) on binder-free and large area plastic chip electrodes. Cu_xNi_1-xS NSs show superior overall water splitting with optimized Cu-amount. The synthesized catalysts perform well in 1.0 M KOH alkaline media for simultaneous hydrogen and oxygen evolution, with relatively low overpotential, efficient kinetics, and sustained electrolysis durability. Impressively, it is found that Cu-doping enhances the chemical and environmental stability, beneficial for the practical application. By modifying the electronic structure, Cu-atom doping promotes the easy flow of electrons, which leads to incredible rise in the electrocatalytic activity with over potential of 152 mV for HER and 189 mV for OER on Cu_xNi_1-xS. Bi-functional water splitting cell generates 10 mA/cm² current density at cell voltage of 1.74 V. Encouragingly, current density of 80 mA/cm² can be generated at potential of 2.61 V with optimized chemical composition of Cu_xNi_1-xS based electrodes. Cu_xNi_1-xS demonstrates excellent stability for bi-functional water electrolysis at 20 mA/cm² for more than 18 h. This research lays forth a viable technique for developing enhanced bi-functional electrocatalysts that can be used to substitute noble metals in a range of renewable energy applications.