Dual active site bridging adsorption mechanism of Ni-WO₃ for boosting urea electrolysis at large current density

Nickel-based catalysts have recently become promising candidates for urea electrolysis. However, their application is hindered by strong interaction with *COO intermediates. Herein, oxyphilic WO₃ is introduced into Ni to construct dual active sites for regulating reaction intermediate adsorption. Experimental results and theoretical calculations reveal that electron transfer from Ni to WO₃ creates electron-deficient Ni, which induces the binding of the -NH₂ group to Ni and anchors the CO group on WO₃. This site-specific adsorption forms a bridging Ni-NCO-W configuration that lowers the C-N bond cleavage energy barrier. Pathway analysis indicates that *COO intermediates preferentially occupy WO₃ sites while N₂ evolution occurs at Ni sites, thereby enabling coupled desorption and reducing the *COO desorption barrier. Consequently, the optimized catalyst achieves a high urea oxidation reaction (UOR) current density of 1000 mA cm^-2 at 1.44 V_RHE, which is 2.2 times that of Ni. Meanwhile, it maintains stable operation at 1000 mA cm^-2 for 300 h in a membrane electrode assembly. This work provides valuable insights into dual active site engineering for Ni-based catalysts in urea electrolysis applications.