NF@Ni3S4@CoFe-LDHs electrode for urea-assisted alkaline oxygen evolution reaction

Anodic oxygen evolution reaction (OER) with high overpotential is the key half reaction of water electrolysis. Urea oxidation reaction (UOR) with a theoretical overpotential of 0.37 V was used to decrease the anodic overpotential. Heterogeneous core-shell structure NF@Ni3S4@CoFe-LDHs electrode was synthesized via electrochemical deposition of CoFe-LDHs on NF@Ni3S4 which was constructed in situ on nickel foam (NF) substrate by hydrothermal method. The hierarchical structure of NF@Ni3S4@CoFe-LDHs electrode accelerated the adsorption of intermediate products and the proton desorption on the electrode surface in the process of urea-assisted OER. At a current density of 100 mA/cm2, the electrode presented an overpotential of 283 mV in 1 mol/L KOH electrolyte with a Tafel slope of 55.9 mV/dec. In the mixed electrolyte of 0.10, 0.33 and 0.50 mol/L urea and 1 mol/L KOH, the electrode required 1.33 V vs. RHE to obtain the current density of 10 mA/cm2. In 0.33 mol/L urea and 1 mol/L KOH electrolyte, the electrode could maintain stability for 20 h. © 2023 Fine Chemicals. All rights reserved.