Enhanced photocatalytic activity of bimodal mesoporous titania powders by C-60 modification

In this work, fullerene modified TiO2 nanocomposites (denoted as C-60/TiO2) with low C-60 loadings (0-1.5 wt.%) have been prepared by a simple hydrothermal method using tetrabutylorthotitanate (TBOT, Ti(OC4H9)(4)) as the titanium precursor. The as-prepared C-60/TiO2 nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, UV-visible spectrophotometry, nitrogen adsorption, and X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy. The formation of hydroxyl radicals ((OH)-O-center dot) on the surface of UV-illuminated TiO2 is probed by photoluminescence using terephthalic acid as a probe molecule. Our results have demonstrated that C-60 molecules can be dispersed as a monolayer onto bimodal mesoporous TiO2 via covalent bonding. The photocatalytic oxidation rate of gas-phase acetone over C-60/TiO2 nanocomposites is greater than that over pure TiO2, commercial Degussa P25 (P25) and C-60-TiO2 counterparts prepared by simple impregnating mixing. In particular, 0.5 wt.% C-60/TiO2 nanocomposites show the greatest photocatalytic activity with the rate constant k exceeding that of P25 by a factor of 3.3. Based on the results of the current study, we propose that C-60 molecules doped onto TiO2 act as electron acceptors responsible for the efficient separation of photogenerated charge carriers and the enhancement of photocatalytic activity. The proposed mechanism for the observed photocatalytic performance of C-60/TiO2 nanocomposites is further corroborated by experiments on hydroxyl radical and transient photocurrent response.