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Direct continuous hydrothermal synthesis of high surface area nanosized titania

Zhang, ZC; Brown, S; Goodall, JBM; Weng, XL; Thompson, K; Gong, KN; ... Darr, JA; + view all (2009) Direct continuous hydrothermal synthesis of high surface area nanosized titania. J ALLOY COMPD , 476 (1-2) 451 - 456. 10.1016/j.jallcom.2008.09.036.

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Abstract

Nanosized TiO2 powder of high surface area was prepared from an aqueous solution of titanium(IV) bis(ammonium lactato) dihydroxide using a continuous hydrothermal flow synthesis (CHFS) reactor which uses superheated water at 400 degrees C and 24.1 MPa as a crystallizing medium. Freeze-dried nano-TiO2 was heat-treated in air over a range of temperatures and then the resulting powders were characterized using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), BET surface area measurement, and Raman spectroscopy. The particle size of the 'as-prepared' TiO2 made using CHFS was ca. 4.8 nm (by HR-TEM), and grew with increasing heat-treatment temperature. It was found that the onset of the anatase-rutile transition of heat-treated nano-TiO2 in air occurred at 500 degrees C and reached 100% rutile at 900 degrees C. The Raman band (E-g) at similar to 150 cm(-1) of anatase (nano-TiO2) softens as the particle size increases with heat-treatment temperature (up to 600 degrees C). The photocatalytic activity of the TiO2 powders for the decolourisation of methylene blue dye was assessed. The effects of nano-TiO2 anatase-rutile phase composition, crystallinity, and crystallite size on the catalytic activity were investigated. (C) 2008 Elsevier B.V. All rights reserved.

Type:Article
Title:Direct continuous hydrothermal synthesis of high surface area nanosized titania
DOI:10.1016/j.jallcom.2008.09.036
Keywords:Continuous hydrothermal flow synthesis, Titanium dioxide, Size dependence, Photocatalyst, ENHANCED PHOTOCATALYTIC DEGRADATION, CHEMICAL-VAPOR-DEPOSITION, INDOOR AIR PURIFICATION, METAL-ION DOPANTS, TIO2 THIN-FILMS, METHYLENE-BLUE, AQUEOUS SUSPENSIONS, RAMAN-SPECTROSCOPY, ANATASE, SIZE
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry

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