Photonic decomposition of ultrafine, rutile phasedTiO2 powder in aqueous 4-chlorophenol solutions

Abstract

The redox properties of a homogeneously precipitatedTiO2 rutile powder with aBET surface area of ∼200 m2 g−1, consisting of acicular primary particles, were characterized using a photocatalyticreaction in aqueous 4-chlorophenol, Cu- and Pb-EDTA solutions underultraviolet irradiation. Results were compared to those of commercial P25TiO2 powder with spherical primary particles as well as those of home-made anataseTiO2 powderwith ∼200 m2 g−1 BET surface area. Here, the anatase powder also includes mainlythe primary particles very similar to the acicular shapes of the rutileTiO2 powder. The rutile powder showed the fastest decomposition rate and the largestamount of product in the photoredox, compared with the anatase or P25 powder,while the anatase powder unexpectedly showed the slowest rate and the smallestamount in the same experiments regardless of having almost the same surface area.The excellent photoredox abilities of this rutile powder appear to be due to aspecific powder preparation method, for example a homogeneous precipitationleading to direct crystallization from the solution, regardless of their crystallinestructures, even when the powders have similar particle shapes and surface areas.