Photoactivity of Anatase-Rutile TiO_2 Nanocrystalline Mixtures Obtained by Heat Treatment of Titanium Peroxide Gel

摘要

Nanosized titanium dioxide photocatalysts with anatase structure or mixture of anatase and rutile phases have been synthesized. Homogeneous precipitation of aqueous solutions containing TiOSO_4 and ammonia and following treatment with H_2O_2 was used to prepare porous yellowish (Ti-Per) gel. The gel was lyophilized for 48h and (Ti-Per)LYO-powder was obtained. Single phase anatase TiO_2 samples were prepared by heating of the (Ti-Per)LYO powder. The lamella like particle morphology of TiO_2 samples determined by SEM were stable in air up to 950°C.The structure evolution during heating of the starting (Ti-Per)LYO powder was studied by DTA and XRD analyses in overall temperature range of phase transformation. The morphology and microstucture characteristics were also obtained by HRTEM and BET methods. The photocatalytic activity of the sample titania TI-LYO/950 heated to 950°C in air contained 78.4% anatase and 21.6% rutile was higher than standard Degussa P25. Titania sample TI-LYO/950 reveals the highest catalytic activity during the photocatalyzed degradation course of 4-chlorophenol in aqueous suspension under UV-irradiation.