Nitrogen-Doped CoP Electrocatalysts for Coupled Hydrogen Evolution and Sulfur Generation with Low Energy Consumption.

Hydrogen production is the key step for the future hydrogen economy. As a promising H2 production route, electrolysis of water suffers from high overpotentials and high energy consumption. This study proposes an N-doped CoP as the novel and effective electrocatalyst for hydrogen evolution reaction (HER) and constructs a coupled system for simultaneous hydrogen and sulfur production. Nitrogen doping lowers the d-band of CoP and weakens the H adsorption on the surface of CoP because of the strong electronegativity of nitrogen as compared to phosphorus. The H adsorption that is close to thermos-neutral states enables the effective electrolysis of the HER. Only -42 mV is required to drive a current density of -10 mA cm-2 for the HER. The oxygen evolution reaction in the anode is replaced by the oxidation reaction of Fe2+ , which is regenerated by a coupled H2 S absorption reaction. The coupled system can significantly reduce the energy consumption of the HER and recover useful sulfur sources.