Preparation of Tungsten Carbide and Titania Nanocomposite and Its Electrocatalytic Activity for Methanol

Abstract: Tungsten carbide and titania nanocomposite with a core-shell structure was fabricated by combing chemical immersion with carbonization-reduction, using titania nanopowder as a support and tungsten hexachloride as a tungsten precursor. The crystal phase, morphology, microstructure, and chemical composition of the sample were characterized by X-ray diffraction, transmission electron microscopy, high resolution scanning transmission imaging, and energy dispersive spectroscopy (EDS). The results show that the crystal phase of the sample is composed of rutile, Ti4O7, WC, W2C, and WxC. The tungsten carbide particles coat onto the surface of the rutile support and thus form a core-shell structure. The electrocatalytic activity of the sample for methanol was measured by cyclic voltammetry with a three-electrode system in an alkaline solution. The results indicate that the electrocatalytic activity of the sample is higher than that of a pure titania phase and WC. The improvement in electrocatalytic activity is related to the reduction-carbonization time, the W to Ti molar ratio, the completeness of the shell layer in the core-shell structure, and the crystal phase of the sample. These factors can be correlated to a synergistic effect between titania and tungsten carbide in the nanocomposite. These imply that titania is a suitable support for the enhancement of the electrocatalytic activity of tungsten carbide.