Surface modification of titanium dioxide nanoparticles by polyaniline via an in situ method

BACKGROUND: Nanoparticulate titanium dioxide (TiO2) has the advantages of high chemical stability, high photocatalytic activity to oxidise pollutants in air and water, relatively low price and non-toxicity. However, its high surface energy leads to the aggregation of nanoparticles. In addition, the wide band gap of TiO2 (3.2 eV) only allows it to absorb ultraviolet (UV) light (<387nm), which represents just a small fraction (3-5%) of the solar photons. These factors have limited its use in many fields. In this study, nanoparticulate TiO2 was modified by polyaniline (PANI) in order to enhance its photoactivity under UV light and sunlight illumination. RESULTS: TiO2 nanoparticles were modified by PANI via a chemical oxidative method. The introduction of small amounts of PANI enhanced the dispersion of TiO2 nanoparticles and improved the photocatalytic activity under UV light. In addition, the band gap energies of all PANI/TiO2 nanocomposites were lower than that of neat TiO2 nanoparticles, so the PANI/TiO2 nanocomposites can be excited to produce more electron-hole pairs under sunlight, which could result in higher photocatalytic activities. CONCLUSION: The modification of nanoparticulate TiO2 by PANI can increase its photoactivity in the process of phenol degradation under UV light and sunlight illumination. (C) 2008 Society of Chemical Industry