Fe-Doped Ni2P/NiSe2 Composite Catalysts for Urea Oxidation Reaction (UOR) for Energy-Saving Hydrogen Production by UOR-Assisted Water Splitting.

ABSTRACT

The development of efficient urea oxidation reaction (UOR) catalysts helps UOR replace the oxygen evolution reaction (OER) in hydrogen production from water electrolysis. Here, we prepared Fe-doped Ni2P/NiSe2 composite catalyst (Fe-Ni2P/NiSe2-12) by using phosphating-selenizating and acid etching to increase the intrinsic activity and active areas. Spectral characterization and theoretical calculations demonstrated that electrons flowed through the Ni-P-Fe-interface-Ni-Se-Fe, thus conferring high UOR activity to Fe-Ni2P/NiSe2-12, which only needed 1.39 V vs RHE to produce the current density of 100 mA cm-2. Remarkably, this potential was 164 mV lower than that required for the OER under the same conditions. Furthermore, EIS demonstrated that UOR driven by the Fe-Ni2P/NiSe2-12 exhibited faster interfacial reactions, charge transfer, and current response compared to OER. Consequently, the Fe-Ni2P/NiSe2-12 catalyst can effectively prevent competition with OER and NSOR, making it suitable for efficient hydrogen production in UOR-assisted water electrolysis. Notably, when water electrolysis is operated at a current density of 40 mA cm-2, this UOR-assisted system can achieve a decrease of 140 mV in the potential compared to traditional water electrolysis. This study presents a novel strategy for UOR-assisted water splitting for energy-saving hydrogen production.