Photocatalytic Reduction of Cr~(VI) by TiO2/GO Nanocomposite

摘要

Graphene Oxide (GO) was successfully deposited on TiO2 NPs through sol-gel process. The fabricated TiO2/GO (T/G) nano-composite was used for reduction of Cr~(VI) under simulated solar light illumination. 10 wt. % GO was used for the preparation of T/ G nanocomposite. Several analytical methods such as powder X-ray diffraction (PXRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and UV-visible diffuse reflectance spectra (DRS) spectrophotometer was used to characterize the samples. The PXRD revealed the formation of the anatase phase of TiO2 NPs and T/G nanocomposites, as per literature more favourable form of TiO2 for photocatalytic activity. The average crystallite size was found 5.1 nm and 23 nm forTiO2 NPs and T/G nanocomposite respectively. Under the simulated sunlight illumination, the TiO2 NPs was excited to generate the electron-hole pairs and then the photo-generated electron transferred by the GO to the Cr~(VI) which further converted into Cr~(III). The band gap for T/G nanocomposite was calculated 2.92 eV. Under visible light,27.3% photoreduction of (10mg/L) Cr~(VI) solution at λ_(max)=347 nm was achieved within 90 min on the T/G sample at the pH 5-6 while overall reduction was 48% including adsorption. The rate of reaction was found 0.00305 min~(-1) and the order of reaction was pseudo first order.