Nickel‐Based Hollow Spheres with Optimized Interfacial Electronic Structures by Highly Dispersed MoN for Efficient Urea Electrolysis

Abstract Ni‐Mo‐based catalysts that exhibit well‐synergized and readily accessible catalytic sites are ideal catalysts for achieving efficient electrocatalysis. Herein, the synthesis of hollow Ni spheres with a hierarchical nanosheet surface modified by highly dispersed MoN for efficient urea electrolysis is reported. This synthesis is based on the design of hollow Mo‐Ni precursors featuring a nanosheet array surface, achieved through the phosphomolybdic acid (PMo 12 )‐mediated reconstruction of hollow Ni‐BTC spheres. The optimized MoN‐Ni catalyst can effectively drive both the urea oxidation reaction (UOR) and hydrogen evolution reaction at low potentials of 1.37 V and 191 mV, respectively, achieving a current density of 100 mA cm −2 . The electrolytic cell utilizing these catalysts can sustain 100 mA cm −2 at a low voltage of 1.53 V and can operate continuously for over 220 h. The X‐ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analyses demonstrate the established built‐in electric field facilitates electron transfer from MoN to Ni, optimizing the d‐band center and consequently reducing the reaction barrier for the UOR. In situ electrochemical impedance spectroscopy (EIS) and in situ Fourier‐transform infrared spectroscopy analyses indicate that MoN promotes the formation of high‐valent Ni sites, which accelerates the UOR and facilitates the urea eletrolysis through a more environmentally friendly “carbonate” pathway.