Immobilization of cobalt doped rutile TiO2 on carbon nanotubes walls for efficient photodegradation of 2,4dichlorophenol under visible light

In this work, we focused on improvement of rutiletype TiO2 degradation efficiency by cobalt doping and decorating on carbon nanotubes walls (CNTs) (CoTiO2/CNTs). We also synthesized pure TiO2, CoTiO2 and TiO2/CNTs samples for control experiments. The textural and morphology features of the samples were characterized by a range of analyses including: XRD, FESEM/EDX. FTIR, TEM, UVVis DRS and N2 physisorption. The XRD results indicated that we obtained rutile phase as the major phase for TiO2 with crystal size between 1822 nm. The band gap energy of the samples calculated from DRS analysis and KubelkaMunk spectra and obtained 2.88, 2.38, 2.97 and 2.20 eV for TiO2, CoTiO2, TiO2/CNTs and CoTiO2/CNTs respectively. The effectiveness of the samples was examined through degradation of 2,4dichlorophenol (2,4DCP) as a model of organic pollutants in the synthetic wastewater under visible light. We achieved 27% and 50% visible light degradation of 2,4DCP in the presence of pure TiO2 and CoTiO2/CNTs after 180 min irradiation, respectively. The high visible light activity of CoTiO2/CNTs sample could be approved that the presence of cobalt and CNTs reduced the band gap energy and sensitize TiO2 surface to visible light. The mechanism for degradation of 2,4DCP by CoTiO2/CNTs photocatalyst under visible light was proposed.