Novel spindle-shaped nanoporous TiO2 coupled graphitic g-C3N4 nanosheets with enhanced visible-light photocatalytic activity

Highly efficient visible-light-driven heterojunction photocatalysts, spindle-shaped nanoporous TiO2 coupled with graphitic g-C3N4 nanosheets have been synthesized by a facile one-step solvothermal method. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption analysis and UV-vis diffuse reflectance spectrometry (DRS), proving a successful modification of TiO2 with g-C3N4. The results showed spindle-shaped nanoporous TiO2 microspheres with a uniform diameter of about 200 nm dispersed uniformly on the surface of graphitic g-C3N4 nanosheets. The g-C3N4/TiO2 hybrid materials exhibited higher photocatalytic activity than either pure g-C3N4 or nanoporous TiO2 towards degradation of typical rhodamine B (RhB), methyl blue (MB) and methyl orange (MO) dyes under visible light (>420 nm), which can be largely ascribed to the increased light absorption, larger BET surface area and higher efficient separation of photogenerated electron-hole pairs due to the formation of heterostructure. In addition, the possible transferred and separated behavior of electron-hole pairs and photocatalytic mechanisms on basis of the experimental results are also proposed in detail.