Synergistic Mo Doping and In Situ Sulfurization Engineering in NiFe LDH/NiFeS Composite toward UOR-Assisted Hydrogen Evolution

The sluggish kinetics of the oxygen evolution reaction (OER) severely limit the efficiency of water electrolysis, rendering the urea oxidation reaction (UOR) an attractive alternative for sustainable hydrogen production. To address this issue, a NiFe layered double hydroxide (LDH) on nickel foam (NF) is sequentially subjected to Mo doping and in situ partial sulfurization, yielding a Mo-NiFe LDH/NiFeS/NF composite. The synergy between Mo incorporation and the resulting LDH/sulfide heterointerface modulates the electronic structure of the active sites, optimizes the adsorption energetics of reaction intermediates, and thus promotes both the UOR and hydrogen evolution reaction (HER). The Mo-NiFe LDH/NiFeS/NF catalyst requires only 1.467 V to deliver 100 mA cm -2 for UOR, substantially outperforming conventional OER catalysts. When employed as both the anode and cathode in a two-electrode urea electrolysis cell, it achieves 100 mA cm -2 at a cell voltage of 1.861 V, with stable operation exceeding 50 h. This work demonstrates a scalable strategy for constructing high-performance bifunctional electrocatalysts toward energy-efficient hydrogen production via UOR-assisted water electrolysis.