Tuning the electron status of urchin-like CoS2 nanowires by selenium doping toward highly efficient hydrogen evolution reaction

Cobalt disulfide (CoS 2 ) for hydrogen evolution reaction (HER) suffers from unfavorable hydrogen adsorption properties due to the strong interaction between the adsorbed H and the intensely electropositive cobalt atom. Herein, we successfully demonstrate a general strategy to improve the hydrogen evolution activity of CoS 2 by modulating the surface electron density. The selenium doped CoS 2 (Se-CoS 2 ) nanowires arrays exhibit a durable activity for electrochemical hydrogen evolution in 0.5 M H 2 SO 4 solution to deliver 10 mA cm −2 at the overpotential of only 139 mV. Our density functional theory studies consistently confirm that the surface electron density of CoS 2 has been effectively manipulated by Se doping. The adsorbed hydrogen binding energy to Se-CoS 2 can be optimized to provide an optimal condition for electron and proton transferring to the adsorbed H 2 , thereby promoting HER activity of CoS 2 .