Multi-walled carbon nanotubes/TiO2 thin layer for photocatalytic degradation of organic pollutant under visible light irradiation

This paper is based on preparation of MWCNT/TiO2 photoactive thin layer deposited on glass substrate using the sol-gel dip-coating technique. The thin layer consists of TiO2 coupled with different amount of per-noncovalent functionalized multi-walled carbon nanotubes (MWCNTs). The optimum MWCNTs/TiO2 weight ratio in the thin film was found to be 1.75 % under the experimental conditions investigated. The MWCNT/TiO2 film was characterized by a range of analytical techniques including: scanning electron microscopy, atomic force microscopy, X-ray diffraction, photoluminescence spectra, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and UV-Vis spectroscopy. The photoactivity of the prepared films, under visible light irradiation, was evaluated by decoloration of methyl orange (MO). Complete decoloration of MO was observed only in 2 h under visible light irradiation. Furthermore, we used chemical oxygen demand (COD) method to determine the degradation efficiency of the MWCNT/TiO2 thin layer. 42 % reduction in COD value of treated MO solution shows substantial degradation of MO by photoactive film. According to the results of MO removal experiment, the excellent activity of the photoactive film can be attributed to the strong interaction between TiO2 particles and MWCNT bundles and the high electron acceptability of CNTs network.