Electrocatalytic Water Splitting through the Ni x S y Self-Grown Superstructures Obtained via a Wet Chemical Sulfurization Process

Abstract We report water-splitting application of chemically stable self-grown nickel sulfide (NixSy) electrocatalysts of different nanostructures including rods, flakes, buds, petals, etc., synthesized by a hydrothermal method on a three-dimensional Ni foam (NiF) in the presence of different sulfur-ion precursors, e.g., thioacetamide, sodium thiosulfate, thiourea, and sodium sulfide. The S2– ions are produced after decomposition from respective sulfur precursors, which, in general, react with oxidized Ni2+ ions from the NiF at optimized temperatures and pressures, forming the NixSy superstructures. These NixSy electrocatalysts are initially screened for their structure, morphology, phase purity, porosity, and binding energy by means of various sophisticated instrumentation technologies. The as-obtained NixSy electrocatalyst from sodium thiosulfate endows an overpotential of 200 mV. The oxygen evolution overpotential results of NixSy electrocatalysts are comparable or superior to those reported previously for other self-grown NixSy superstructure morphologies.