Fullerene C70-TiO2 hybrids with enhanced photocatalytic activity under visible light irradiation

Fullerene C-70 modified TiO2 (C-70-TiO2) hybrids were fabricated through a hydrothermal method from titanium sulfate and functionalized C-70. The structures of the synthesized hybrids were characterized by X-ray diffraction, UV-vis diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area measurements, matrix-assisted laser desorption/ionization-time of flight-mass spectrometry and photoluminescence spectroscopy. The experimental results indicated that the introduction of C-70 slightly reduces the crystallite size of TiO2 while extending its adsorption edge to the visible light region. C-70 dispersed on the surface of TiO2 nanoparticles with covalent bonding, which generated strong interactions between the functionalized C-70 and TiO2. The O-2(center dot-), (OH)-O-center dot and h(+) are active species which were proved by the trapping experiment. The photocatalytic degradation efficiency of sulfathiazole over C-70-TiO2 hybrids is higher than that over pure TiO2, C-60-TiO2, and a mechanical mixture of C-70 and TiO2 under visible light irradiation. The excellent visible light-induced activity is rationalized by the results of photoluminescence spectroscopy; i.e., the intensities of emissions from C-70-TiO2 hybrids were found to be weaker than those from pure TiO2 and C-60-TiO2 hybrid.