Mo 2 C‐Mediated Surface Reconstruction in MoNi 4 @Mo 2 C Heterostructure for Efficient Electrocatalytic Urea Oxidation

ABSTRACT Replacing the oxygen evolution reaction with the urea oxidation reaction (UOR) offers an energy‐saving route for H 2 production, yet rational regulation of surface reconstruction in Ni‐based UOR electrocatalysts remains challenging. Herein, we report a MoNi 4 @Mo 2 C heterostructure and demonstrate its Mo 2 C‐mediated reconstruction of surface Ni species toward NiOOH‐containing active species during UOR. As a result, MoNi 4 @Mo 2 C requires only 1.26 V vs. RHE to reach 10 mA cm −2 and delivers 199.3 mA cm −2 at 1.30 V vs. RHE, outperforming MoNi 4 , Mo 2 C, and most reported Ni‐based UOR electrocatalysts. Electrochemical measurements reveal the dynamic generation, consumption, and regeneration of high‐valent Ni species during UOR. In situ Raman spectroscopy confirms the potential‐dependent formation of NiOOH‐containing active species, while electrochemical impedance measurements demonstrate accelerated charge‐transfer kinetics. When assembled in a two‐electrode electrolyzer, MoNi 4 @Mo 2 C||Pt/C delivers 112.3 mA cm −2 at 1.40 V and lowers the cell voltage by 210 mV at 100 mA cm −2 relative to conventional water electrolysis. This work highlights the importance of Mo 2 C‐mediated surface reconstruction in regulating active Ni species for UOR and offers insights into the rational design of Ni–Mo‐based heterostructures for efficient urea electrolysis.