S-doped Co-based compounds as catalysts for urea electrooxidation and urea-assisted hydrolysis

Replacing dynamics-restricted oxygen evolution reaction (OER) with urea oxidation reaction (UOR) is very important for reducing the thermodynamic potential of water electrolysis. The development of nonprecious metal catalysts with excellent electrocatalytic activity and stability are desired to resolve the slow kinetics resulted from the six electron transfer process inherent in UOR. Here, we design and prepare a slender and dense nanoneedle-like CoP/CoO arrays with sulfur doping (S-CoP/CoO) on nickel foam via a hydrothermal and phosphorization-sulfidation method. S-doping results in electron redistribution around Co, P, modifying the electronic structure of the Co atom surface, making it partially positively charged (+δ), thereby effectively tuning surface properties, enhancing electron conductivity, and improving electrocatalytic activity. As a result, S-CoP/CoO/NF requires an overpotential of 212.5 mV and potential of 1.35 V (vs. RHE) to achieve 10 mA cm −2 for OER and UOR, respectively, and drives the full urea electrolysis at 1.61 V to deliver current density of 10 mA cm −2 along with a good durability. This work will promote research interest in material design for energy conversion technologies and urea-assisted hydrogen production .