Ultra-thin CoS2 nanosheets synthesized by one-step hydrothermal process for hydrogen evolution

Rationally designing and synthesizing nanostructures with increased density of active sites are an effective route to enhance the hydrogen evolution reaction (HER) activity of electrocatalysts. In this work, a simple one-step hydrothermal method was used to synthesize cobalt disulfide (CoS2) nanosheets on the stainless-steel fiber (SSF) felt substrate, by which the thickness of CoS2 nanosheets can be sensitively tuned by thiourea concentration in reactant precursors. Especially, the CoS2 nanosheets synthesized under a thiourea concentration of 0.083 M present an ultra-thin thickness of about 10 nm with abundant gaps between the nanosheets. Such morphology with large effective surface area together with superhydrophilic property assures it an effective HER electrode, showing an overpotential of − 290.6 mV at 10 mA cm−2 and a Tafel slope of 74.21 mV dec−1 over other samples synthesized under higher thiourea concentrations. Chronoamperometric test also shows excellent HER durability by the assistance of chemical-stable SSF substrate.