Highly dispersive {001} facets-exposed nanocrystalline TiO2 on high quality graphene as a high performance photocatalyst

Abstract

A series of composites of nanocrystalline TiO2 with exposed {001} facets and high quality graphene sheets (GS) were synthesized via a one-step hydrothermal reaction in an ethanol–water solvent. The obtained {001} facets-exposed TiO2/GS photocatalysts were characterized by Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction pattern (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet visible (UV-vis) diffuse reflectance spectroscopy (DRS) and Electrical Impedance Spectroscopy (EIS). They showed a better photocatalyst properties than P25 and other normal TiO2/GS composites, which could be explained on the basis of the formation of chemical Ti–O–C bond and the formation of nano-sized Schottky interfaces at the contacts between TiO2 and GS. The influence of the exposed {001} facets on the photocatalytic activity was investigated. The result showed that positively charged dye molecules are preferentially adsorbed onto the TiO2/GS composites due to the photogenerated charge gathered on GS. Overall, this work could provide new insights into the fabrication of TiO2–carbon composites as high performance photocatalysts and facilitate their application in addressing environmental protection issues.