Structure and Photocatalytic Properties of TiO2 Coated Multi-Walled Carbon Nanotubes Prepared by Solvothermal Method

In this study, the nanocomposites of TiO2 coated multi-walled carbon nanotubes (MWCNTs) are prepared by a simple solvothermal method using Ti(SO4)2 ethanol solution and MWCNTs aqueous suspension. The effects of MWCNTs/TiO2 mass ratio (x) and reaction temperature on the structural, optical and photocatalytic properties of these nanocomposites are investigated. It is found that anatase TiO2 nanoparticles are grown and uniformly coated on the surface of MWCNTs, and they are in intimate contact with each other. The amount of anatase phase and the crystal size can be enhanced by increasing the reaction temperature from 120 °C to 180 °C. The new Ti–O–C bond has been formed in these nanocomposites, while the bandgap becomes narrower by increasing the mass ratio (x = 0 ∼ 0.3%). The photocatalytic activity is evaluated by degrading of methyl orange solution under ultraviolet and visible-light irradiation. The optimal reaction temperature for photocatalytic efficiency is found at 150 °C. The photocatalytic activity is improved greatly by coating TiO2 nanoparticles on the MWCNTs surface, and the maximum efficiency is present at x of 0.09%. The photocatalyst can be reused for eight cycles, and it retains over 95% photocatalytic degradation efficiency.