Enhancement effects of Fe-doped Ni3S2 on efficient electrochemical urea oxidation and mechanism insights

The urea oxidation reaction (UOR) can reduce the energy consumption of electrolytic for urea-assisted water splitting to produce hydrogen. Fe(EDTA)-Ni3S2 @NF electrode is prepared by a simple one-step hydrothermal method. The addition of EDTA promotes more Fe atoms doping into Ni3S2. Fe doping regulated the morphology and electronic structure of Ni3S2, and the Fe(EDTA)-Ni3S2 @NF shows excellent UOR activity. The required UOR potentials on Fe(EDTA)-Ni3S2 @NF at 50 mA cm−2 is 1.363 V (vs. RHE). In addition, the kinetics experiments and DFT calculations of the electrode toward UOR are carried out. It is found that UOR reactions under high current density (760 mA cm−2) would be limited. The liquid product of NO2- were detected by ion chromatography for UOR on Fe(EDTA)-Ni3S2 @NF. The faradaic efficiency for the electrooxidation of CO2NH4 to NO2- is 38 %. These findings provide complementary insights for the UOR in water-energy nexus systems.