Facile synthesis of MWO4 (M=Co,Ni, Zn and Cu) nanoarrays for efficient urea oxidation

Urea electrolysis is an attractive strategy for hydrogen evolution, which can reduce the environmental pollution caused by urea-rich wastewater. It is important to note that catalytic performance depends on the electron cloud density configuration around different metals of the same type of material. Herein, a series of well-tuned MWO₄ (M = Co, Ni, Zn and Cu) nanoarrays was in site grown on Ni foam substrates using a single-step hydrothermal process for the first time. It is worth mentioning that as prepared NiWO₄ electrode significantly improves urea oxidation activity with an applied voltage of 1.36 V at 100 mA cm^?2, which is lower than that of CoWO₄ (1.37 V@100 mA cm^?2), ZnWO₄ (1.38 V@100 mA cm^?2) and CuWO₄ (1.42 V@100 mA cm^?2). Experimental and theoretical calculations demonstrate that the superior activity of the electrodes is mainly attributed to the optimal urea adsorption energy, fast electron transfer rate, more active site exposure, lower impedance and better conductivity of the material.