Synthesis and Characterization of Mesoporous H4SiW12O40/TiO2 Composites

MIRTA N. BLANCO; LUIS R. PIZZIO

Handbook of Photocatalysts: Preparation, Structure and Applications

Nova Science Publishers

Lugar: Hauppauge NY; Año: 2009; p. 511 - 526

A series of mesoporous titania materials modified with tungstosilicic acid (TPA) were successfully synthesized by using urea as low-cost template via sol-gel reactions, followed by removing the urea by extraction with water. They were characterized by FT-IR, XRD, DTA-TGA, DRS, TEM and BET. The samples presented mesopores with a diameter higher than 3.0 nm. The SBET of the solids decreases with the increase of the TPA content and with the increase of the calcination temperature. According to FT-IR studies the main species present in the samples is [SiW12O40]4- anions, which was partially transformed into during the calcination step. The XRD patterns of the modified samples only exhibited the characteristic peaks of anatase phase. The presence of TPA retarded the crystallization of the anatase phase and its transformation into rutile phase. The point of zero charge decreased in parallel with the increment of tungstosilicic acid in the samples and with the increase of the calcination temperature. The band gap energy decreased as a result of the introduction of TPA into the TiO2 matrix, but remained practically constant with the increase of the calcination temperature.