Superhydrophilic Bimetallic Sulfide Nanosheets for Hydrogen Production Using Urea-Assisted Electrocatalytic Water Splitting

Electrolysis of industrial and human urea-containing wastewater is beneficial to the environment, and using the urea oxidation reaction (UOR) instead of the oxygen evolution reaction (OER) saves energy and effectively improves the performance of electrocatalytic hydrolysis for hydrogen production. The Co9S8/Ni3S2 nanosheet structures on nickel foam (NF) are an active and hydrophilic catalyst for UOR and the hydrogen evolution reaction (HER). This electrocatalyst needs a low overpotential of 136 mV to attain 10 mA·cm–2 for HER, and it can reach a current density of 100 mA·cm–2 for UOR at a low working potential of 1.36 V vs RHE. The introduction of the Co element regulates both the morphology and the electronic structure. The former results in the Co9S8/Ni3S2/NF offering more active sites with a larger specific surface area for the nanosheet morphology, while the latter drives the S element to move in the direction of low binding energy. The examination of the potential cobalt and nickel sulfides as a bifunctional electrocatalyst for the energy-efficient electrolytic H2 production and the purification of urea-rich harmless wastewater has significantly advanced due to this work.