Binary Ni/NiO–NiWO4 with highly activity and durability for the enhanced oxidation of urea.

Urea oxidation reaction (UOR) can be used as an alternative to oxygen evolution reaction (OER) for hydrogen production by electrolysis of water, and as an anode reaction for direct urea fuel cells (DUFC). However, the slow kinetics of UOR restricts its wide application. Therefore, it is of great significance to design and prepare cheap and high-performance non-noble metal based UOR catalysts. In this work, Ni/NiO–NiWO 4 -2 sample prepared by solvent evaporation method has a mesoporous feature verified by the structural characterization, which is conducive to electrolyte diffusion and electron transport. Electrochemical tests show that the Ni/NiO–NiWO 4 -2 sample has good UOR catalytic activity, namely, the potential required by UOR is 1.669 V (vs RHE) at the current density of 270.44 mA cm−2. The excellent performance of Ni/NiO–NiWO 4 -2 is ascribed to that its mesoporous structure facilitates the diffusion of the electrolyte and exposes more active areas, the existence of metal W weakens the poisoning of Ni3+ active components and reduces the energy barrier of UOR confirmed by density functional theory, thus enhancing the performance of UOR. Ni and W oxides were constructed by solvent evaporation method. In alkaline medium, the current density reached 270.44 mA cm−2@ 1.669V, which is due to W doping regulates electron distribution and reduces energy barrier of UOR confirmed by DFT. [Display omitted] • The UOR catalyst with high activity and stability was constructed by a simple method. • The required voltage of the Ni/NiO–NiWO 4 -2 for UOR is 1.3749 V@10 mA cm−2 in alkaline medium. • W doping effectively weakens the poisoning of Ni3+ active components by intermediates. • W doping effectively reduces the energy barrier of UOR verified by DFT calculation. [ABSTRACT FROM AUTHOR]