Graphene oxide and graphene based catalysts in photochemical ractions

Abstract

Graphene has impressible absorbing ability and its electron transmission capacity makes it a great prosperity in many science horizons. In this study graphene or graphite nitride has been employed as a carrier in order to modify TiO2, ZnO and Ta2O5 photocatalysts.Graphene modified TiO2 particles were obtained by a sol-gel method from titanium isoproproxide (or P25) and reduced graphene oxide (RGO). The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), UV-vis diffuse reflectance (UV-vis DRS) and thermo gravimetric differential thermal analysis (TG-DTA) were investigated over the samples. The diffuse reflectance spectra (DRS) studies indicate that G-TiO2 has a significant light absorption increasing and red shift of absorption peak. G-TiO2 photocatalyst could decompose methylene blue under visible light (> 430 nm). G-TiO2 synthesised from titanium isoproproxide presented better activity than G-TiO2 (P25). The catalysts could also produce ●OH and [O2]- radicals via electron scavengers (peroxymonosulphate, peroxydisulphate and hydrogen peroxide) to enhance degradation process with visible illumination.ZnO loaded RGO photocatalysts were synthesized through Zn powder and graphite oxide. The structural, morphological, and physicochemical properties of the samples were thoroughly investigated by XRD, FT-IR, FE-SEM, UV-visible DRS, TG-DTA, and Raman spectroscopy. Zn powder could successfully reduce GO and ZnO was obtained simultaneously by one-step hydrothermal method. RGO-ZnO photocatalysts could bleach MB under UV-vis illumination.Three different compounds: ammonia, graphene and C3N4 were utilized to dope tantalum pentoxide photocatalyst. Catalysts were analyzed by X-ray diffraction, UV–vis diffuse reflectance spectra and FTIR spectroscopy. The photocatalytic behavior was thorough investigated in bleaching methylene blue under UV-visible illuminations; the modified catalysts could decompose methylene blue, showing better activity than undoped Ta2O5. However, only N-doped Ta2O5 will show activity under visible light.