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

Abstract

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). X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), diffuse reflectance spectroscopy (DRS), and nitrogen physisorption were used to characterize the prepared samples. The XRD results indicated after cobalt doping, we obtained rutile phase as the major phase for cobalt containing samples. The band gap energy of the synthesized samples were calculated by Kubelka-Munk equation using diffuse reflectance spectra. The surface area of the samples was obtained by BET model and average pore diameter and pore volume of the samples were extracted from desorption branch of BJH model. The effectiveness of the samples was examined through degradation of 2,4-dichlorophenol (2,4-DCP) as a model of organic pollutants 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 can be approved that the presence of cobalt and CNTs reduce the band gap energy and sensitize TiO2 surface to visible light respectively. The mechanism for degradation of 2,4-DCP by Co-TiO2/CNTs photocatalyst under visible light is proposed.