1D Composite Nanorods of Cobalt Phosphide-Cobalt Sulfide with Improved Electrocatalyst Performance

Efficient electrocatalysts of cobalt phosphide-cobalt sulfide 1D composite nanorods for hydrogen evolution reaction (HER) are synthesized by heat-treatment of cobalt phosphide nanorod under CS₂ flow. The reaction of cobalt phosphide with CS₂ molecule leads to the formation of CoP−CoS composite with the maintenance of original 1D nanorod morphology. In comparison with the pristine CoP nanorod, the CoP−CoS composite nanorod shows much higher HER electrocatalytic activity with much lower overpotential, highlighting the beneficial effect of composite formation with metal sulfide on electrocatalyst performance of metal phosphide. The composite formation with CoS domain results in the remarkable enhancement of HER kinetics, electrochemical active surface area, and charge transfer kinetics, which is mainly responsible for the enhanced electrocatalytic activity of composite nanorod. The present study underscores that hybridization with metal sulfide can provide an efficient methodology to improve the electrocatalyst functionality of metal phosphide.