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

Abstract

Fullerene C₇₀ modified TiO₂ (C₇₀–TiO₂) hybrids were fabricated through a hydrothermal method from titanium sulfate and functionalized C₇₀. 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 C₇₀ slightly reduces the crystallite size of TiO₂ while extending its adsorption edge to the visible light region. C₇₀ dispersed on the surface of TiO₂ nanoparticles with covalent bonding, which generated strong interactions between the functionalized C₇₀ and TiO₂. The O₂˙⁻, ˙OH and h⁺ are active species which were proved by the trapping experiment. The photocatalytic degradation efficiency of sulfathiazole over C₇₀–TiO₂ hybrids is higher than that over pure TiO₂, C₆₀–TiO₂, and a mechanical mixture of C₇₀ 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 C₇₀–TiO₂ hybrids were found to be weaker than those from pure TiO₂ and C₆₀–TiO₂ hybrid.