Visible light photocatalytic activities of carbon nanotube/titanic acid nanotubes derived-TiO2 composites for the degradation of methylene blue

•Carbon nanotube/TiO2 composites have been prepared by a hydrothermal method.•Titanic acid nanotubes have been used as the TiO2 precursor of the composites.•The visible-light photocatalytic degradation of methylene blue has been carried out.•BET surface area, MWCNT content and hydrothermal reaction time affect activity.

Carbon nanotube/TiO2 composites were synthesized by hydrothermal method using titanic acid nanotubes as the TiO2 precursor. The crystalline structures, morphologies, light absorption properties, specific surface areas of the prepared powders were investigated with XRD, TEM, UV–Vis absorption spectra and N2 adsorption–desorption. The photocatalytic activities of the composites were evaluated by monitoring the degradation rate of methylene blue (MB) under the visible light irradiation. The mechanism of the improved photocatalytic activity of the photocatalyst was discussed. It was found that all of the composites upon 24 h of hydrothermal reaction show the diffraction peaks indexed to anatase TiO2 and the critical reaction time for anatase TiO2 nanoparticles to form is 3 h. The visible light photocatalytic activities of the catalysts in this experiment were affected by a combination of BET specific surface area, MWCNT content and hydrothermal reaction time.

Graphical abstractCarbon nanotube/TiO2 composites were synthesized by hydrothermal method using titanic acid nanotubes as the TiO2 precursor. The role played by MWCNT can be illustrated by injecting electrons into TiO2 conduction band under visible light irradiation and triggering the formation of very reactive radicals superoxide radical ion O2− and hydroxyl radical OH, which are responsible for the degradation of MB.Figure optionsDownload full-size imageDownload as PowerPoint slide