Accelerated Hydrogen Evolution Reaction in CoS₂ by Transition-Metal Doping

Cobalt pyrite (CoS2) is one of the promising candidate catalysts for electrocatalytic hydrogen evolution because of its efficient catalytic activity sites and inherent metallicity. Herein, we report the greatly improved electrocatalytic activity of CoS2 resulting from Mn doping. First, we give the theoretical prediction that Mn is the most excellent dopant to activate the electrocatalytic activity of CoS2 with the smallest Gibbs free energy (|ΔGH*|) while remaining metallic. Second, to provide experimental evidence, Mn-doped CoS2 nanowires are prepared by a hydrothermal and postsulfuration method. The optimized sample shows a low overpotential of 43 mV at 10 mA/cm2, a Tafel slope of only 34 mV/dec, and long-time stability for the hydrogen evolution reaction. This work reveals a new way to stimulate the electrocatalytic activity of other pristine candidate catalysts.