Hierarchical structure based on Fe, Mo co-doped Ni₃S₂ and NiFe LDH: Dual-anode boosting efficient hydrogen evolution

Hydrogen energy serves as a secondary energy carrier, and water electrolysis for hydrogen production is a core development direction. By combining the cathode hydrogen evolution reaction (HER) with the dual anode reactions—oxygen evolution reaction (OER) and urea oxidation reaction (UOR), it simultaneously achieves mainstream alkaline electrolytic hydrogen production and urea treatment. Here, Ni₃S₂(Fe, Mo)-NiFe LDH, a trifunctional electrocatalyst, is prepared via a two-step hydrothermal method. Density functional theory (DFT) calculations confirmed that co-doping with Mo and Fe optimizes Gibbs free energy of hydrogen adsorption $\left(\mathrm{\Delta }{G}_{{\mathrm{H}}^{\ast }}\right)$ of Ni₃S_2. The doping-modulated Ni₃S₂(Fe, Mo) and NiFe LDH form a hierarchical structure, not only achieving performance complementarity but also further enhancing the overall catalytic activity through interfacial electronic interactions. At 10 mA·cm^–2, the HER overpotential is 91 mV, and the UOR overpotential is 74 mV, which is a reduction of 154 mV compared to OER (228 mV). Moreover, the constructed HER‖OER (HER‖UOR) electrolyzer operates at a voltage as low as 1.55 V (1.41 V), along with 100 h stability.