Document Type: Research Paper
Caspian Faculty of Engineering, College of Engineering, University of Tehran
Hybridnanomaterials and Environment Laboratory, Faculty of Fouman, College of Engineering, University of Tehran, Iran.
Faculty of Chemical Engineering, College of Engineering, University of Tehran, Iran.
University of Applied Science and Technology, Guilan, Iran.
In this work, we focused on improvement of rutile-type TiO2 degradation efficiency by cobalt doping and decorating on carbon nanotubes walls (CNTs) (Co-TiO2/CNTs). We also synthesized pure TiO2, Co-TiO2 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, UV-Vis DRS and N2 physisorption. The XRD results indicated that we obtained rutile phase as the major phase for TiO2 with crystal size between 18-22 nm. The band gap energy of the samples calculated from DRS analysis and Kubelka-Munk spectra and obtained 2.88, 2.38, 2.97 and 2.20 eV for TiO2, Co-TiO2, TiO2/CNTs and Co-TiO2/CNTs respectively. The effectiveness of the samples was examined through degradation of 2,4-dichlorophenol (2,4-DCP) as a model of organic pollutants in the synthetic wastewater under visible light. We achieved 27% and 50% visible light degradation of 2,4-DCP in the presence of pure TiO2 and Co-TiO2/CNTs after 180 min irradiation, respectively. The high visible light activity of Co-TiO2/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 2,4-DCP by Co-TiO2/CNTs photocatalyst under visible light was proposed.