A novel preparation of mesoporous CsxH3-xPW12O40/TiO2 nanocomposites with enhanced photocatalytic activity

Nanocomposite photocatalysts, cesium hydrogen salts of 12-tungstophosphoric acid coupled with anatase TiO2 (CsxH3-xPW12O40/TiO2), x=0.5, 1.0, 1.5, 2.0, 2.5, and 3.0, respectively), were prepared via one-step sol-gel method followed by hydrothermal treatment at 200 degrees C with a heating ramp of 2 degrees C/min. Several characterization techniques, UV-vis diffuse reflectance spectroscopy (UV-vis/DRS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) patterns, Raman scattering spectroscopy, field emission scanning electron microscopy (FESEM), and N-2 adsorption/desorption analysis, were combined to confirm the structure integrity of the Keggin units in the composites and investigate the phase structure and optical absorption properties, morphology, and surface textural properties of the composites. The photocatalytic activities of CsxH3-xPW12O40/TiO2 were evaluated by the degradation of three model organic molecules including 4-nitrophenol (4-NP), methyl orange (MO), and rhodamine B (RB) under UV-light irradiation. For comparison, the photocatalytic activities of the parent CsxH3-xPW12O4 and Degussa P25 were studied under the same conditions. The results showed that as-prepared nanocomposite photocatalysts were substantially more effective than the starting CsxH3-xPW12O4 and Degussa P25. The high photoactivities of as-prepared nanocomposites could be attributed to the higher surface acidity, mesoporosity, and the synergistic effect existed between the CsxH3-xPW12O4 and the TiO2 matrix. (C) 2007 Elsevier B.V. All rights reserved.