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 H 2 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 Fe 2+ , which is regenerated by a coupled H 2 S absorption reaction. The coupled system can significantly reduce the energy consumption of the HER and recover useful sulfur sources.