カーボン被覆アナターゼ-カーボン層の役割

Abstract

Carbon-coated anatase-type TiO_2 was prepared by the heat treatment of the powder mixtures of photocatalyst TiO_2 (ST-01) with poly (vinyl alcohol) at a temperature between 700-900℃ for 1 h in Ar gas flow. Carbon layers formed on TiO_2 particles were confirmed to be porous and responsible for large apparent BET surface area measured on carbon-coated anatase, consequently for large amount of methylene blue (MB) adsorption from its aqueous solution. Apparent rate constant k of the samples for MB decomposition depended on the crystallinity of the anatase phase evaluated from the full width at half maximum intensity (FWHM) of 101 diffraction line. This rate constant k was found to be determined as a balance among the crystallinity improvement of anatase phase, the suppression of the phase transformation of anatase to much less active rutile and the decrease in UV rays reached on the surface of TiO_2, three of them being controlled by carbon layer.