Interface-engineered amorphous-crystalline Mo/NixS heterojunctions for efficient urea electrooxidation

Abstract

Developing nickel-based urea oxidation reaction (UOR) catalysts with low-cost, high activity is still in challenges. In this work, we report an amorphous Mo/crystalline Ni_xS heterojunction (A/C-Mo/Ni_xS) through a dual-phase engineering strategy involving sulfurization of nickel foam followed by magnetron-sputtered Mo deposition. Remarkably, the optimized A/C-Mo/Ni_xS achieves an ultralow potential of 1.42 V (vs. RHE) at 50 mA cm⁻², while maintaining stable operation over 60 h with negligible activity decay. Characterization results reveal that the crystalline Ni_xS substrate provides excellent electrical conductivity through its ordered atomic arrangement, whereas the amorphous Mo overlayer creates abundant unsaturated coordination sites that synergistically optimize urea adsorption and intermediate stabilization. Particularly, the unique amorphous-crystalline interface induces strong electronic coupling between Mo and Ni_xS, which not only accelerates the dehydrogenation kinetics of *CONH₂ intermediates but also effectively suppresses Ni leaching through enhanced charge transfer.