Strengthening CuNiCoMo medium-entropy alloy by tuning local lattice tensile strain and built-in electric field for boosting urea oxidation reaction

Developing high-performance catalysts for electrocatalytic urea oxidation reaction (UOR) is significant in treating urea-rich wastewater but remains a considerable challenge. Herein, CuNiCo-7.8 %Mo/CF (7.8 % is the Mo atom percentage; CF: copper foam) medium entropy alloy catalyst with moderate local lattice tensile strain and built-in electric field is prepared by solvothermal and calcination methods to obtain the good UOR performance. Besides, the operando electrochemical impedance and quasi-operando Raman spectroscopy proved that CuNiCo-7.8 %Mo/CF can favor the direct oxidation reaction in a solution of 1.0 M KOH and 0.5 M urea. The electrochemical results show that CuNiCo-7.8 %Mo/CF has a better UOR activity (E10/500/1000 = 1.27/1.44/1.51 V) than other studied samples during the UOR process. Meanwhile, CuNiCo-7.8 %Mo/CF can stably work for 100 h at 1000 mA cm−2. Therefore, a CuNiCo-7.8 %Mo/CF material is designed for high-efficiency UOR at large current density and it is provided as a feasible method for large-scale treating urea-rich wastewater. [Display omitted] •Adjusting the local lattice tensile strain of CuNiCo MEA by adding Mo atoms.•Addition of Mo induces the generation of built-in electric field in the CuNiCo MEA.•The direct oxidation reaction mechanism is explored during the UOR process.•CuNiCo-7.8 %Mo/CF shows good UOR performance at ampere-level current density.