Strategic cation exchange induced 2D nickel sulphide nanoplates with enhanced oxygen evolution reaction performance

Nickel sulphides stand out as promising, earth-abundant transition metal chalcogenides with significant potential for the electrocatalytic oxygen evolution reaction. However, the realisation of their full potential is hindered by challenges in controlling the size, morphology and phase of nickel sulphide nanocrystals, limiting their broader application. In this study, we introduce a novel method for synthesising two-dimensional Ni₉S₈ phase-dominated Ni_xS nanoplates via a precisely controlled cation exchange approach. Through meticulous adjustments in surface ligands and reaction temperature, we effectively fine-tune the reaction kinetics, resulting in the production of Ni_xS nanoplates with well-preserved morphology and high crystallinity. Notably, the resulting Ni_xS nanoplates synthesised at 170 °C exhibit exceptional performance in the oxygen evolution reaction, boasting a low overpotential of 329 mV at a current density of 10 mA cm⁻² and a Tafel slope of 52 mV dec⁻¹. These findings not only advance our understanding of nickel sulphide nanomaterials but also hold promise for their practical applications in efficient and sustainable electrocatalytic processes.