Nanostructured Ni2P-C as an Efficient Catalyst for Urea Electrooxidation

Nickel-based materials are a type of cost-effective catalyst for urea oxidation. Herein, we first reported nanostructured Ni2P-C as an efficient catalyst for urea electrooxidation. The Ni2P-C catalyst was prepared by a facile hydrothermal method and the structure and morphology were further characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The hexagonal crystal structure for Ni2P was indicated by the characteristic peaks in the XRD patterns, and lattice fringes of Ni2P were clearly observed in the high-resolution TEM images. The catalytic ability for urea electrooxidation was studied by cyclic voltammetry and chronoamperometry techniques. It was found that the current density at 0.5 V was ca. 70.4 mA cm(-2), about 2.7 times higher than that of the referenced commercial nickel oxide catalyst. A good catalytic stability for urea oxidation was also obtained. A diffusion-controlled process was observed for urea oxidation on Ni2P catalyst while the active sites arising from Ni(II) ion oxidation was following a surface-redox-reaction-controlled process. Kinetics studies by impedance spectroscopy and Tafel slope analysis displayed improved charge-transfer kinetics towards urea electrooxidation. The results demonstrated that Ni2P would have potential applications for catalytic urea oxidation.