Preparation and Visible Light Photocatalytic Activity of Titanium Dioxide Coated Multiwalled Carbon Nanotubes

Abstract

Titanium dioxide coated multiwalled carbon nanotubes (MWCNTs) composite photocatalysts were prepared by the controllable oxidation of titanium carbide coated MWCNTs obtained by the molten salt method using MWCNTs as a reaction template and metal titanium powder as a titanium source. The effects of the molten salt reaction temperature, the molar ratio of MWCNTs to titanium powder, and the oxidation temperature on the structure and morphology of the products were investigated. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The photodegra- dation of a methylene blue (MB) solution was used to evaluate the photocatalytic activity of the catalyst under visible light irradiation (λ420 nm). The results suggest that the TiO2 coated MWCNTs keep the similar fibred morphology with the pristine MWCNTs. Uniform and fine well-dispersed TiO2 coatings on the surface of MWCNTs closely contact with the MWCNTs support and Ti-O-C chemical bonds form between them. The prepared TiO2/MWCNTs photocatalyst shows higher visible light photocatalytic activity because the MWCNTs increase the adsorption of methylene blue on the photocatalyst and an impurity state is formed close to the valence band of titanium dioxide, which can enhance the absorption and utilization of solar energy.