Supercritical fluid processing for the synthesis of NiS2 nanostructures as efficient electrocatalysts for electrochemical oxygen evolution reactions

Abstract

In this work, the synthesis of NiS₂ nanostructures using a simple and one-step environmentally benign supercritical fluid processing technique within 60 min of reaction time has been demonstrated. Structural and morphological characterization has been performed to confirm that the as-synthesized products are cubic NiS₂ nanostructures. Interestingly, the as-prepared NiS₂ nanostructures exhibit superior electrocatalytic activity towards the oxygen evolution reaction with a small overpotential of 264 mV vs. RHE at 10 mA cm⁻² and a Tafel slope of 105 mV dec⁻¹. Remarkably, the observed catalytic activity of the NiS₂ nanostructures bears close resemblance to that of the benchmark IrO₂ catalyst, where IrO₂ shows an overpotential of 260 mV with a Tafel slope of 95 mV dec⁻¹. Thus, the as-synthesized NiS₂ nanostructures can be considered as a promising material for the replacement of noble metal-based IrO₂ catalysts.