Halloysite–TiO2 nanocomposites: Synthesis, characterization and photocatalytic activity

Authors: Dimitrios Papoulis, Sridhar Komarneni, Dionisios Panagiotaras, Elias Stathatos, Despina Toli, Konstantinos C. Christoforidis, Marcos Fernández-García, Huihui Li, Shu Yin, Tsugio Sato, Hiroaki Katsuki

Abstract:
Two halloysite–TiO₂ nanocomposites were prepared with two different tubular halloysite clays by depositing anatase-TiO₂ on the halloysite surfaces using titanium isopropoxide under hydrothermal treatment at 180 ^◦C. The nanocomposites were characterized by X-Ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), attenuated total reflection using Fourier transform infrared spectroscopy (ATR-FTIR), absorption properties by UV–vis spectroscopy and N₂ specific surface area (SSA) analysis by BET method. Good dispersion of 3–10 nm TiO₂ particles on halloysite external surfaces was achieved in both the halloysite–TiO₂ nanocomposites and ATR-FTIR results showed the formation of hydrogen bonding between TiO2 and the outer surfaces of halloysite tubes. After treating with TiO₂, both halloysite samples largely showed interparticle mesopores of about 5.7 nm. However, the macropores of halloysite (lumen or central hole in halloysite tubes) were not detected probably as a result of plugging of the lumens in halloysite tubes by TiO₂ nanoparticles. These nanocomposites were tested for their photocatalytic activities in decomposing NO_x gas and toluene. The halloysite–titania samples showed significantly higher activity in decomposing NO_x gas under visible-light irradiation ( l > 510 nm) and UV–visible light irradiation (l > 290 nm) compared to that of the standard commercial titania photocatalyst, P25. In addition, composite photocatalyst showed larger catalytic activity either under sunlight or pure UV irradiation in decomposing toluene compared to the commercial titania, P25. Our experimental data suggest that the enhanced photocatalytic activity is related with the good dispersion of the TiO₂ nanocrystals on the surface of the clay minerals.

Keywords:
Halloysite
Titania
Nanocomposite
Photocatalytic activity

Published in: Applied Catalysis B: Environmental (Volumes 132–133, Pages 1-552, 27 March 2013)

Publisher: Elsevier  

ISSN Information: 0926-3373

Halloysite–TiO2 nanocomposites: Synthesis, characterization and photocatalytic activity

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