Activating and Optimizing Activity of CoS2 for Hydrogen Evolution Reaction through the Synergic Effect of N Dopants and S Vacancies

Here, N-doped cobalt pyrite (CoS2) electrocatalytic material is developed via utilizing the synergic effect of N dopants and S vacancies. The catalyst displays high activity and stability for hydrogen evolution reaction. Density functional theory calculations and electrochemical characterizations reveal that the electrochemical activity of the CoS2 catalyst is directly associated with the content of N dopants and S vacancies, where proper combinations of N dopants and S vacancies yield a minimized overpotential close to that of commercial Pt. What's more, optimized performance has been achieved by carefully manipulating the amounts of N dopants and S vacancies in N-doped CoS2 catalyst, which exhibits a Tafel slope as small as 48 mV/dec, an ultralow overpotential of 57 mV at 10 mA/cm2, and satisfying stability. This work highlights a feasible strategy to explore efficient electrocatalysts via nonmetal element doping and defect engineering.