Self-Derivation and Surface Reconstruction of Fe-Doped Ni3S2 Electrode Realizing High-Efficient and Stable Overall Water and Urea Electrolysis

Exploring earth-abundant, highly effective, and stable electrocatalysts for overall water and urea electrolysis is urgent and essential for developing hydrogen energy technology. Herein, a simple self-derivation method is used to fabricate a Fe-doped Ni₃S₂ electrode. The electrode exhibits an impressive trifunctional catalyst, with low overpotentials of 290, 198, and 254 mV at 100 mA cm⁻² for the oxygen evolution reaction (OER), urea oxidation reaction (UOR), and hydrogen evolution reaction (HER). The durability is higher than 3500 h (146 days) at 100 mA cm⁻² for the OER without obvious change. In situ Raman spectra reveal the incorporation of Fe inhibited S dissolution and facilitates the catalyst reconstruction. The density functional theory calculations indicate that the doping of Fe optimizes the adsorption of the rate-determining step and the d-band center is closer to the Fermi level, which accelerates the OER process. The two-electrode electrolyzer needs the cell voltages of only 1.76 and 1.57 V to achieve a current density of 100 mA cm⁻² and remarkable durability for more than 500 h at 100 and 500 mA cm⁻² for overall water and urea splitting. This work holds great promise for industrial water and urea splitting applications.