S dopant-mediated hydrogen evolution reaction activity of CoSe2.

CoSe 2 has become one of the most appealing non-noble metal catalysts for hydrogen evolution reaction (HER) in the field of electrolysis water due to its abundant resources and good activity. Inversely, its slow kinetic behavior is still restrained, which plays a negative influence for high-efficiency HER. Herein, a certain of Ni or S was introduced into the (100) crystal facet of CoSe 2 on the basis of density functional theory (DFT) calculations. Thermodynamic calculation results reveal that the HER activity for CoSe 1 S 1 is relatively better than those of Ni 0.375 Co 0.625 Se 2 and pristine CoSe 2 when a certain of S atoms were introduced into CoSe 2. More strikingly, the active sites of CoSe 1 S 1 are reversed from cationic Co to anion S, which is close to the ideal value (0) of Gibbs free energy. Meanwhile, the kinetic performance of H adsorbed on the anionic S or Se site is optimal, and their migration energy barrier is lower in comparison with 1/2 of the cationic Co site. According to the electronic structure analysis, the conductivity of CoSe 1 S 1 is prominent than other counterparts (such as Ni 0.375 Co 0.625 Se 2 and CoSe 2). This work indicates that CoSe 1 S 1 exhibits an excellent catalytic performance for HER, and offers theoretical guidance in the aspect of experiments for designing high-efficient HER catalysts. [Display omitted] • The doping of S into Se sites of CoSe 2 was systematically investigated. • The CoSe 1 S 1 presented more active sites and high conductivity. • The S sites in CoSe 1 S 1 are thermodynamically beneficial for HER catalysis. • The kinetic rate of S sites is superior to that of Co within CoSe 1 S 1. [ABSTRACT FROM AUTHOR]