Enhanced photocatalytic activity of bimodal mesoporous titania powders by C60 modification

Abstract

In this work, fullerene modified TiO₂ nanocomposites (denoted as C₆₀/TiO₂) with low C₆₀ 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 C₆₀/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) on the surface of UV-illuminated TiO₂ is probed by photoluminescence using terephthalic acid as a probe molecule. Our results have demonstrated that C₆₀ molecules can be dispersed as a monolayer onto bimodal mesoporous TiO₂via covalent bonding. The photocatalytic oxidation rate of gas-phase acetone over C₆₀/TiO₂ nanocomposites is greater than that over pure TiO₂, commercial Degussa P25 (P25) and C₆₀–TiO₂ counterparts prepared by simple impregnating mixing. In particular, 0.5 wt.% C₆₀/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 C₆₀ 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 C₆₀/TiO₂ nanocomposites is further corroborated by experiments on hydroxyl radical and transient photocurrent response.