immobilization of cobalt doped rutile tio2 on carbon nanotubes walls for efficient photodegradation of 2,4-dichlorophenol under visible light

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 expriments.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 were 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.