Vesicle-Shaped Co-Ni-S designed by first principles screening and d-Band center control for active hydrogen evolution

Abstract

Hydrogen evolution reaction (HER) is considered as an effective pathway for hydrogen production. Herein, to obtain efficient HER catalyst, density functional theory is employed to figure out the optimal candidate for nickel sulfide. Guided by the mechanistic screening, the highly active HER electrocatalyst, Co-substituted Ni₃S₄, is synthesized by one-step hydrothermal method, resembling a vesicle composed of a broken spherical membrane and encapsulated clusters of nanospheres. Cracks on membrane provide a rational entry for reactant molecules to be enclosed in the vesicle. Additionally, the enhanced intrinsic activity also attributes to the upward shift of the d-band center. From the reaction energy diagrams, the decomposition of H₂O* is confirmed as the rate-determining step (RDS) and the energy required for the RDS is efficiently lowered by the elevated d-band center, which made the catalyst achieves 185 mV overpotential at 100 mA·cm⁻² and 38 mV at 20 mA·cm⁻² lower than utmost Co-Ni-S relative electrocatalyst.