In situ synthesis and enhanced visible light photocatalytic activity of C-TiO2 microspheres/carbon quantum dots

TiO2 microspheres and TiO2/carbon quantum dots (CQDs) composites with different CQDs contents were successfully synthesized via solvothermal and in situ hydrothermal method. The structure and morphology of the prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM). Results showed that carbon elements were successfully doped into the TiO2 lattice (C-TiO2) and CQDs were hybrid with C-TiO2 microspheres. The X-ray photoelectron spectroscope (XPS), valence band XPS (VB-XPS) and UV-vis diffuse reflectance spectra (DRS) analyses revealed that carbon doped into TiO2 microspheres could lead to local energy levels in the band structure and generate valence band tails to absorb visible light. The photocatalytic activities of these samples were evaluated by the photodegradation of Rhodamine B (RhB) under visible light irradiation. C-TiO2/CQDs samples presented an enhanced photocatalytic performance compared with pristine TiO2, which could be attributed to the present of CQDs, acting as adsorption sites for RhB molecules and charge separation centers to impede the recombination and prolong the life time of electron and hole pairs.