Enhancement of photocatalytic activity of Mesporous TiO powders by hydrothermal surface fluorination treatment

Mesporous surface-fluorinated TiO (F-TiO) powders of anatase phase with high photocatalytic activity are prepared by a one-step hydrothermal strategy in a NHHF-HO-C HOH mixed solution with tetrabutylorthotitanate (Ti(OCH), TBOT) as precursor. The prepared samples are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, N adsorption-desorption isotherms, UV-vis absorption spectroscopy, and transmission electron microscopy. The production of hydroxyl radicals (OH) on the surface of UV- illuminated TiO is detected by a photoluminescence (PL) technique with use of terephthalic acid as a probe molecule. The photocatalytic activity is evaluated by photocatalytic oxidation decomposition of acetone in air under UV light illumination. The results show that the photocatalytic activity of F-TiO powders is obviously higher than that of pure TiO and commercial Degussa P25 (P25) powders due to the fact that the strong electron-withdrawing ability of the surface ≡Ti-F groups reduces the recombination of photogenerated electrons and holes, and enhances the formation of free OH radicals. Especially, the F-TiO powder prepared at the nominal atomic ratio of fluorine to titanium (RF) of 0.5 shows the highest photocatalytic activity and its rate constant κ exceeds that of P25 by a factor of more than 3 times.