Effects of Trifluoroacetic Acid Modification on the Surface Microstructures and Photocatalytic Activity of Mesoporous TiO₂ Thin Films

Abstract

Enhancement of the photocatalytic activity of sol-gel-derived TiO2 thin films by a simple treatment with trifluoroacetic acid (TFA) was investigated. The thin films were characterized with N2 adsorption, Fourier transform infrared spectroscopy, UV-visible spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, X-ray diffraction, atomic force microscopy, and differential thermal analysis/ thermogravimetry analysis. The photocatalytic activity of the thin films was evaluated by the photocatalytic decomposition of acetone in air. The results show that TFA is chemisorbed on the surface of the TiO2 films as a trifluoroacetate complex. The photocatalytic activity of modified TiO2 thin films is higher than that of unmodified TiO2 thin films, and the modified film treated at 250 °C shows the highest activity. This is ascribed to the fact that the TFA complex bound on the surface of TiO2 acts as an electron scavenger and, thus, reduces the recombination of photogenerated electrons and holes. The enhancement is only temporary, however, as the TFA eventually decomposes under the strong oxidizing environment of photocatalysis. Reaction schemes are proposed to explain the interaction between TFA and TiO 2. This detailed study may shed some light on the future development of more durable enhanced photocatalysts.

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“…Sol-gel TiO 2 film R a (nm), mean ± SD R q (nm), mean ± SD R z (nm), mean ± SD R max (nm), mean ± SD Z max (nm), mean ± SD agreement with the results reported in literature [29]. Grain boundaries become less sharp and the matrix shows a smoother appearance.…”

Mesoporous titania photocatalysts: preparation, characterization and reaction mechanisms

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Reactivity of CO2and H2O on TiO2catalysts studied by gas phase FT-IR method and deactivation mechanism

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