Photocatalytic Degradation Studies using Nanocomposite of Co and N Co-doped TiO2 Nanotubes and Reduced Graphene Oxide

Abstract

Many types of dyes are used in textile industries and the contaminated water is expelled as it is without any treatment for the removal of dyes and harmful reagents which pose threats to human and animal health because some dyes are dangerous to chronic level. They have many short-term impacts such as skin sensitization and nausea to lingering impacts like cancer. Photocatalysis is an advanced technique from nanochemistry having many applications in daily life which cover areas from clean energy production and self cleaning surfaces to environmental protection. In this research, TiO2 and graphite were used for the preparation of TiO2 nanotubes and graphene oxide, respectively. TiO2 nanotubes were prepared by hydrothermal method and Hummers’ method was used for the graphene oxide synthesis. Co-doping of cobalt and nitrogen was done on TiO2 catalysts which resulted in narrowing of band gap with increase in efficiency and thus making the process more economical. Urea and cobalt nitrate were used as nitrogen and cobalt dopant precursors, respectively. Nitrogen concentration was kept constant and cobalt was taken in 4 different concentrations i.e 0.2, 0.4, 0.6 and 0.8 g. The obtained catalysts were characterized by FT-IR, DRS, SEM, TGA, BET, XRD and EDX for the investigation of attached functional groups, band gap, morphology, thermal stability, surface area, phase and composition, respectively. Additionally the effects of doped amount of cobalt ions on the optical properties and photocatalytic activity of co-doped TiO2 nanotubes were investigated. Methyl orange was selected for the degradation study. The results exhibited that photocatalytic performance of 4-CoN-TNT is best amongst all in the visible light. It shows efficiency of 88%. To further improve the efficiency the best catalyst was selected for the nanocomposite preparation with reduced graphene oxide. Hydrothermal method was used for nanocomposite formation and in situ reduction of graphene oxide was carried out. Again the degradation study was carried out against methyl orange. The efficiency was increased up to 93%.