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Improved high-temperature stability and sun-light-driven photocatalytic activity of sulfur-doped anatase TiO(2)

Periyat, P, Pillai, SC, McCormack, DE, Colreavy, J and Hinder, SJ (2008) Improved high-temperature stability and sun-light-driven photocatalytic activity of sulfur-doped anatase TiO(2) JOURNAL OF PHYSICAL CHEMISTRY C, 112 (20). 7644 - 7652. ISSN 1932-7447

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Abstract

Of the various forms of titania (anatase, rutile and brookite) anatase is found to be the best photocatalyst. Without any chemical additives, the anatase to rutile transformation in pure synthetic titania usually occurs at a temperature range of 600 to 700 °C. High temperature (≥800 °C) stable photoactive anatase titania is required for antibacterial, application in building materials. A simple methodology to extend the anatase phase stability by modifying the titanium isopropoxide precursor by sulphur modification using sulphuric acid is presented. Chemical synthesis by sol-gel method involved the reaction of titanium tetraisopropoxide (TTIP) with sulphuric acid (H2SO4), followed by hydrolysis and condensation. The xerogel formed after drying was subjected to further calcination at different temperatures. Various TTIP:H2SO4 molar ratios such as, 1:1, 1:2, 1:4, 1:8 and 1:16 were prepared and these samples characterized by XRD, DSC, Raman spectroscopy, XPS and BET surface area analysis. Sulphur modified samples showed extended anatase phase stability up to 900 ºC, while the control sample prepared under similar conditions completely converted to rutile phase at 800 ºC. Stoichiometric modification up to 1:4 TTIP: H2SO4 composition (TS4) was found to be most effective in extending the anatase to rutile phase transformation by 200 °C compared to the control sample and it shows 100 % anatase at 800 °C and 20 % anatase at 900 ºC. Samples of 1:4 TTIP:H2SO4 composition calcined at various temperatures such as 700, 800, 850 and 900 ºC showed significantly higher photocatalytic activity compared to the control sample. The 1:4 TTIP:H2SO4 composition calcined at 850 ºC showed the highest photoactivity and it decolorized the rhodamine 6G dye within 12 minutes (rate constant 0.27 min-1) whereas the control sample prepared under identical condition decolorized the dye after 80 minutes (rate constant 0.02 min-1). It was also observed that the optimal size for highly photoactive anatase crystal is ca. 15 nm. XPS studies indicated that the retention of the anatase phase at high temperatures is due to the existence of small amounts of sulphur up to 900 °C.

Item Type: Article
Additional Information: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry C. copyright © American Chemical Society after peer review and technical editing by the publisher.To access the final edited and published work see http://dx.doi.org/10.1021/jp0774847
Uncontrolled Keywords: Science & Technology, Physical Sciences, Technology, Chemistry, Physical, Nanoscience & Nanotechnology, Materials Science, Multidisciplinary, Chemistry, Science & Technology - Other Topics, Materials Science, TITANIUM-DIOXIDE NANOMATERIALS, ORIENTED THIN-FILMS, SOL-GEL ROUTE, VISIBLE-LIGHT, NANOCRYSTALLINE TITANIA, PHASE-STABILITY, BAND-GAP, METHYLENE-BLUE, PARTICLE-SIZE, METAL-OXIDES
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Divisions: Faculty of Engineering and Physical Sciences > Mechanical Engineering Sciences
Depositing User: Symplectic Elements
Date Deposited: 16 Nov 2012 11:03
Last Modified: 23 Sep 2013 19:52
URI: http://epubs.surrey.ac.uk/id/eprint/738082

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