Insight into the synergistic effect between nickel and tungsten carbide for catalyzing urea electrooxidation in alkaline electrolyte

Tungsten carbide modified nickel (Ni-WC/C) catalyst is synthesized through the sequential impregnation method and evaluated for the electrooxidation of urea in alkaline electrolyte. Both the activity and stability of Ni are enhanced by the introduction of WC. In situ Fourier transform infrared (FTIR) measurements combined with electrochemical analysis were used to provide a better understanding of the mechanism for urea electrooxidation on the Ni-based catalysts. The formation of CO2 and NCO− species is detected during urea oxidation, and the synergistic effect resulting from the interaction of Ni and WC is also proposed. The Ni-WC/C electrode contributes to the improved C–N bond cleavage in urea than that on Ni/C, resulting in a higher activity. Furthermore, the introduction of WC also enhances the anti-poisoning ability, thus promoting more complete oxidation of urea to produce CO2, which leads to a higher energy conversion efficiency than that on Ni/C. This work provides a new strategy for designing highly efficient catalysts for urea electrooxidation.