Synthesis of Ni3S2 catalysts using various sulphur sources and their HER and OER performances

Abstract

It is highly anticipated that hydrogen can be produced via water splitting, and can be electrocatalyzed using non-precious electrocatalysts. Accordingly, nickel sulfide (Ni₃S₂) has attracted considerable attention due to its high electrochemical performance for the hydrogen evolution reaction and oxygen evolution reaction. In this study, nano-sized Ni₃S₂ binder-free electrodes were directly grown on Ni foam using various methods. The obtained results showed that the interconnected sheet-like Ni₃S₂ with a hydrophilic surface, which was prepared from Na₂S via the hydrothermal method, exhibited the best HER and OER electrocatalytic performance. Its thin nanosheet structure could offer more active centers for the HER and OER in the aqueous alkaline electrolyte and its hydrophilic surface could also facilitate the transfer of ions at the interface of the electrode and electrolyte. The best Ni₃S₂ electrode synthesized using Na₂S exhibited an overpotential of 43 mV and 127 mV at the current density of 10 mA cm⁻² and 100 mA cm⁻², respectively. Furthermore, it also exhibited superior electrochemical activity and durability for the OER.