Synthesis of visible-light-active nanosize rutile titania photocatalyst by low temperature dissolution–reprecipitation process

Titania nanocrystals were prepared by a “low temperature dissolution–reprecipitation process” (LTDRP) in liquid media. The crystallization of amorphous precursor could proceed at low temperature around room temperature, which was much lower than those of conventional calcination and hydrothermal reactions. The thermodynamically stable rutile formed at low temperature below 70 °C, while the metastable anatase formed at higher temperature. The phase composition, microstructure, morphology, and specific surface area of titania changed significantly depending on the reprecipitation temperatures. Needle-like rutile titania and spherical anatase titania crystals with high specific surface areas were prepared. Well-crystallized needle-like nanosize rutile crystals possessed higher photocatalytic activities than those of anatase crystals under visible light irradiation of wavelength >400 and/or >510 nm.