Interface engineering of S-doped Co2P@Ni2P core–shell heterostructures for efficient and energy-saving water splitting

Abstract

Electrochemical hydrogen production is largely limited by the sluggish anodic oxygen evolution reaction (OER). Urea-assisted energy-saving alkaline hydrogen production has been promising alternative pathway. Herein, we demonstrate an ion-exchange strategy to fabricate cobalt phosphide nanowire decorated with nickel phosphide nanosheets core@shell heterostructured arrays with sulfur doping at the interface (S-Co2P@Ni2P) for both hydrogen evolution reaction (HER) and urea oxidation reaction (UOR). Interfacial S-doping induces charge transfer from S-Co2P to Ni2P in the heterostructure, generating electron-rich Ni centers and electron-deficient Co centers to be active sites for HER and UOR, respectively, with optimized absorption/desorption energies of reactants/products to accelerate the catalytic kinetics of HER and UOR. As a result, S-Co2P@Ni2P requires an overpotential of 103 mV and potential of 1.36 V (vs. RHE) to achieve 100 mA cm−2 for HER and UOR, respectively, and drives the full urea electrolysis at 1.43 V to deliver current density of 10 mA cm−2.