Amorphous Ni(OH) 2 -Ni 3 S 2 /NF nano-flower heterostructure catalyst promotes efficient urea assisted overall water splitting.

Urea assisted overall water splitting represents a cost-effective and efficient technology for hydrogen production, which not only obviates the generation of explosive H 2 and O 2 gas mixture but also minimizes the energy cost for the water splitting. In this study, we employed a one-pot hydrothermal method to directly synthesize Ni(OH) 2 -Ni 3 S 2 /NF hybrid nanoflowers on a nickel foam (NF) substrate, resulting in efficient and stable bi-functional electrocatalysts for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER). Under alkaline conditions, the Ni(OH) 2 -Ni 3 S 2 /NF catalyst exhibits low voltage requirements of 1.346 V and -0.014 V vs. RHE with a current density of 10 mA cm -2 for UOR and HER, respectively. Furthermore, when employing the Ni(OH) 2 -Ni 3 S 2 /NF catalyst as both anode and cathode for urea-assisted overall water splitting, it requires a cell voltage of merely 1.396 V with a current density of 10 mA cm -2 , which is notably lower than the voltage required for complete water decomposition at the same current density (1.568 V vs. RHE). The one-step synthesis of the Ni(OH) 2 -Ni 3 S 2 /NF catalyst lays a foundation for further exploration of other transition metal complexes as dual-function electrocatalysts, enabling energy-efficient electrolytic hydrogen production and the treatment of urea-rich wastewater.