PHOTOCATALYTIC DECOMPOSITION OF HALOGENATED ORGANICS OVER NANOCRYSTALLINE TITANIA

A systematic study of particle size effect on nanocrystalline TiO2 pho tocatalysts was performed by evaluating their photoreactivity in the d ecomposition of chloroform. TiO2 anatase particles with well-controlle d sizes (6, 11, and 21 nm) and high surface areas were synthesized via chemical precipitation with hydrothermal treatment or post calcinatio n. The powders derived were found to have narrow size distribution by TEM. A blue shift of the absorption edge with decreasing particle size was observed in UV-visible photoabsorption spectroscopy, correspondin g to the size-quantization effect in the nanocrystalline particles. Th e highest photoreactivity was achieved by hydrothermally synthesized p articles with an intermediate nanocrystallite size of 11 nm. (C) 1997 Acta Metallurgica Inc.