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.