Application of nanostructured graphene oxide/titanium dioxide composites for photocatalytic degradation of rhodamine B and acid green 25 dyes

Graphene oxide/TiO2 (X wt% GO/TiO2, X = 3, 7, 10, 12 and 15) composites were synthesized by a hydrothermal method followed by calcination treatment at 300, 400 and 550 °C. These composites exhibit high efficiency for photocatalytic degradation of organic dyes such as rhodamine B (Rh B) and acid green 25 (AG-25) under UV-visible light irradiation. The photocatalytic degradation efficiency was influenced by the GO content, calcination temperature, dye concentration, photocatalyst dose, hydrogen peroxide concentration and initial pH. The samples were systematically evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results showed good distribution of TiO2 nanoparticles on the GO surface. A significant enhancement in the photocatalytic degradation of dyes was achieved using 10 wt% GO/TiO2 treated at 400 °C as a photocatalyst compared to pristine TiO2 and/or other prepared samples, i.e., complete degradation of Rh B after 75 min and approximately 96% of acid green 25 after 180 min. This enhancement in photocatalytic degradation efficiency is attributed to the GO sheets, which are characterized by a high surface area that increases the adsorption capacity, a strong electron transfer ability and 2D, thin layers.