An efficient composite growing N-doped TiO2 on multi-walled carbon nanotubes through sol-gel process

High-activity, visible-light-driven photocatalysts were prepared by forming N-doped TiO2 on multi-walled carbon nanotubes (MWCNTs). The use of MWCNTs as the support in a N-doped TiO2 system favored electron trapping, because the recombination process could be retarded, thus promoting photocatalytic activity. The prepared photocatalysts were systematically characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunaure-Emmett-Teller (BET) spectroscopy, and UV-Vis diffuse reflectance spectroscopy (UV-Vis/DRS). The results indicated that the N-doped TiO2 coated on MWCNTs improved the surface area and slightly modified the optical properties of the composite. The activities of the photocatalysts were probed by photodegradation of methanol in the presence of visible light irradiation. The experimental results revealed that the strong interphase linkage between the MWCNTs and the N-doped TiO2 played a significant role in improving photocatalytic activity. However, the mechanical process for MWCNT-TiO2-xNx mixtures showed lower activity than just pure N-doped TiO2. In this study, N-doped TiO2 precursors coated with pretreated MWCNTs during a sol-gel process could effectively form a MWCNT-TiO2-xNx composite. The composite showed excellent activity and effectively enhanced the efficiency of N-doped TiO2 under the visible light region.