Photocatalysis of TiO2 – Supported Graphene Oxide and its Reduced Form towards Phenol Degradation

Abstract

Commercial nanocrystals graphite was oxidized to graphene oxide (GO) using Hummers’ method. Then, GO was directly impregnated mechanically over TiO2 (GOTi) and reduced later using a stream of hydrogen gas in a controlled reactor at 450 oC (H2RGOTi) or reduced initially by hydrazine hydrate solution (HH) in a 1000-W microwave oven then loaded later on TiO2 (HHRGOTi). Also, hydrothermal reduction was applied to obtain reduced GO/TiO2 (RGOTi). X-ray photoelectron spectroscopy (XPS), Raman spectra and X-ray diffraction patterns (XRD) confirmed the oxidation and reduction processes of graphite and GO respectively. XPS have revealed that GO surface consists mainly of hydroxyl, epoxy, carbonyl and carboxylic groups. From argon bombardment etching, it was revealed that GO is on the surface of TiO2. Catalysts were prepared and tested for photodegradation of phenol under UV illumination in presence and absence of hydrogen peroxide. In addition, the photocatalytic activity of the as-prepared catalysts was compared with commercial TiO2. It was concluded that the 0.1-RGOTi catalyst has the best performance in terms of phenol degradation under UV illumination in absences and presence of H2O2. However, its performance is better in presence of H2O2 especially at small time intervals.