Extending the accessibility of catalytic active sites through L-cysteine assisted sulphidation for promoting hydrogen evolution reaction

Abstract

Green hydrogen production is highy focussed in recent times on implementing the use of sustainable fuels in the future energy economy. One of the most effective ways to produce green hydrogen is electrocatalyts by overall water splitting producing hydrogen which is clean and green. Various researchers have been on persistant exploration made this topic the research hotspot in understanding the catalysis mechanism and developing new novel materials. As hydrogen evolution reaction (HER) kinetically limits the overall water splitting reactions, this work demonstrates the L-cysteine assisted synthesis of millerite nickel sulfide dispersed as particles on nickel foam (NS/NF) by a simple one-step hydrothermal process as a self-supported working electrode. The controlled phase of the NiS is confirmed from XRD and TEM analysis and the size and morphology of the catalyst is characterised by SEM anlaysis. XAS analysis explores more into the bulk structure and chemical coordination within the crsytal system by XANES and EXAFS findings. The HER performance of NS/NF catalyst exhibits superior activity than bare NF requiring 140 mV for delivering the current density of -10 mAcm-2 having Tafel slope of 112.3 mV dec-1. The catalyst demonstrated excellent durability for 20 h with further electro-activating NS/NF under reduction conditions. In two-electrode system, NS/NF||RuO2 required only 1.79 V as the overall cell votage for generating 10 mAcm-2 current density. This study illustrates simple and facile synthetic route for NiS synthesis with extendable ECSA demonstrating superior HER activity over time under alkaline condtions.