New Insight for Enhanced Photocatalytic Activity of TiO₂ by Doping Carbon Nanotubes: A Case Study on Degradation of Benzene and Methyl Orange

Abstract

A carbon nanotubes (CNT)/TiO 2 nanocomposite photocatalyst has been prepared by a simple impregnation method, which is used, for the first time, for gas-phase degradation of benzene. It is found that the asprepared CNT/TiO 2 nanocomposite exhibits an enhanced photocatalytic activity for benzene degradation, as compared with that over commerical titania (Degussa P25). A similar phenomenon has also been found for liquid-phase degradation of methyl orange. The characterization of photocatalysts by a series of joint techniques, including X-ray diffraction, transmission electron microscopy, ultraviolet/visible (UV/vis) diffuse reflectance spectra, and photoluminescence spectra, discloses that CNT has two kinds of crucial roles in enhancement of photocatalytic activity of TiO 2 . One is to act as an electron reservoir, which helps to trap electrons emitted from TiO 2 particles due to irradiation by UV light, therefore hindering electron-hole pairs recombination. The other is to act as a dispersing template or support to control the morphology of TiO 2 particles in the CNT/TiO 2 nanocomposite, and this important role was neglected in previous studies. Accordingly, a reasonable model is proposed to expain the role of CNT in CNT/TiO 2 composites as a photocatalyst for degradation of organic pollutants.

Facile hydrothermal preparation of titanium dioxide decorated reduced graphene oxide nanocomposite

“…The most likely explanation is that the relatively weak and broad characteristic peak of graphene at 24.5 degrees was masked by the strong (101) TiO 2 reflections at 25.4 degrees. 60 Transmission electron micrographs of the samples are shown in Figure 3 along with the size distributions of the TiO 2 nanoparticles. The nanoparticles were distributed uniformly on the basal plane of RGO nanosheets.…”

Synthesis of Carbon Nanotube–Anatase TiO2 Sub-micrometer-sized Sphere Composite Photocatalyst for Synergistic Degradation of Gaseous Styrene

“…30 All samples exhibited the typical absorption with an intense transition in the UV region of the spectra except the purified MWCNTs attributing to the electron transition of TiO 2 from the valence band to conduction band. 10,31,44 Further investigation indicated that no obvious variation for the absorption intensity in UV region was observed for the composite photocatalysts with different MWCNTs contents. This might be because that the MWCNTs were mostly covered by the TiO 2 spheres.…”

Syntheses of Carbon Nanotube-Metal Oxides Composites; Adsorption and Photo-degradation

“…The first is adsorption ability of the nanotubes since the adsorption is a key process in the catalytic destruction of organic pollutants. While the second is the electron transfer from nanoparticels into the nanotubes, in other words the electron injection (Xu et al, 2010& Martinez et al, 2011. In general, irradiation of metal oxide semiconductor with a photon of sufficient energy, greater or equal to band gap energy could promote an electron from valence band (VB) to conduction band (CB).…”