Zinc and Nitrogen Co-doped TiO2/ Graphene Oxide Nanocomposites for Photocatalytic Degradation of Methyl Orange

Abstract

Textile industry contributes to 17 to 20% waste water pollution because of its intensive use of dyes. Dyes pose a significant threat to the environment due to their toxic nature. The most efficient method considered for the removal of these dyes is photocatalysis. Recent research on semiconductors has proven that TiO2 is the best semiconductor so far for degradation of dyes. Having a large band gap of 3.2ev, fast electron hole recombination, TiO2 absorbs only UV range of light. In this thesis, an effort to enhance its properties was done via codoping with a non-metal (Nitrogen) and a metal (Zinc) and then making a composite with graphene oxide (GO) nanosheets. TiO2 nanoparticles were prepared using Sol-Gel method and varying concentrations of zinc (0.1%, 0.5%, 1%, and 2%) were used while keeping nitrogen concentration constant. Methyl orange (MO) is used to study the degradation activity in visible light. 2% Zn/N-codoped TiO2 showed maximum activity of 80% in 24 hours. GO nanosheets were synthesized using Hummers method. Composites were formed using the best prepared catalyst and GO with varying ratios of GO (0.5:1, 1:1, 2:1) using Hydrothermal method. Further degradation studies were done using the prepared nanocomposites. The nanocomposites exhibited enhanced photocatalytic activity of 85% against MO in 10 hours. Various characterization techniques involving SEM, XRD, EDS, UV/Vis-spectroscopy were used to analyze the prepared nanoparticles & nanocomposites. Overall decrease in both grain size and crystallite size was observed.