Amorphous Ni(OH)₂‐Ni₃S₂/NF nano‐flower heterostructure catalyst promotes efficient urea assisted overall water splitting

Abstract

Urea assisted overall water splitting represents a cost‐effective and efficient technology for hydrogen production, which not only obviates the generation of explosive H₂ and O₂ 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‐Ni₃S₂/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‐Ni₃S₂/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‐Ni₃S₂/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‐Ni₃S₂/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.