In situ grown CoS on nickel foam pre-deposited with sulphur as an efficient OER electrocatalyst

Abstract

CoS-related catalysts usually have good OER activity, but require very complicated preparation processes, so the corresponding mechanism analysis will proceed with difficulty. In this work, a NiCo-150 composite catalyst is prepared via a simple two-step electrodeposition method with an outstanding OER performance of 145 mV@10 mA cm⁻² and 337 mV@50 mA cm⁻². The Ni-150 composite catalyst shows a good OER performance, but the OER performance is further improved after electrodepositing CoS, and is better than that of a simple CoS/NF composite catalyst. The experimental results show that this pre-deposition in situ growth technique effectively reduces the internal resistance of the electrochemical process and significantly increases the electrochemically active sites by controlling the morphology. In order to explain the catalytic mechanism, the valence changes of Co, Ni, and S were detected by XAS measurements. The results show that the Co ion may be the most important active center.