Copper and Nitrogen co-doped TiO2/ Graphene Oxide Nanocomposites for Photocatalytic Degradation of Methyl Orange

Abstract

Photocatalysis based on semiconductors is a likely approach to overcome many pollution problems and eliminate toxic organic compounds from waste-water. TiO2 due to its unique properties is considered as a promising semiconductor. Despite its intriguing properties, TiO2 is unable to absorb visible part of light due to which the overall photocatalytic activity is affected. In this thesis, TiO2 nanoparticles were synthesized in its pure anatase phase using sol-gel method. To reduce the band gap, N doped TiO2 and N and Cu codoped TiO2 nanoparticles with varying concentrations of Cu (0.1%, 0.5%, 1%, 2%, 3 wt %)were synthesized to obtain both non-metal and metal dopant properties. Tetra titanium iso-propoxide, urea and Cu (NO3)2.3H2O were used as precursors for TiO2 nanoparticles and N and Cu doping, respectively. The prepared catalysts were characterized using XRD, SEM, EDS, FT-IR and UV/Vis-DRS. Both crystallite size and particle size for doped catalysts were reduced as compared to pure TiO2 nanoparticles. The degradation studies for the prepared photocatalysts were performed on methyl orange under visible light using LEDs. The kinetic studies exhibited that photocatalytic performance of 2% Cu/N co-doped TiO2 was best amongst all prepared catalysts with an efficiency of 93%. To further improve the efficiency, nanocomposites of the as-prepared best catalyst and graphene oxide were prepared. GO nanosheets were prepared using Hummers’ method by using graphite flakes as a precursor and KMnO4 as an oxidizing agent. Incorporation of 2% Cu/N co-doped TiO2 nanoparticles on GO sheets was done by using hydrothermal method and different percentages of GO: TiO2 (0.5:1, 1:1 and 2:1) were prepared to study the effect of amount of GO. Degradation studies were performed on methyl orange again and the kinetic studies showed that the efficiency was increased to 96%.