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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/13718

Title: Systematic evaluation of thermal and mechanical stability of different commercial and synthetic photocatalysts in relation to their photocatalytic activity
Authors: Ribbens, S.
Beyers, E.
Mertens, Myrjam
Ke, X.
Bals, Sara
Van Tendeloo, G.
Meynen, Vera
Cool, P.
Issue Date: 2012
Abstract: The effect of thermal treatment and mechanical stress on the structural and photocatalytic properties of eight different (synthetic and commercial) photocatalysts has been thoroughly investigated. Different mesoporous Ti-based materials were prepared via surfactant based synthesis routes (e.g. Pluronic 123, CTMABr = Cetyltrimethylammonium bromide) or via template-free synthesis routes (e.g. trititanate nanotubes). Also, the stabilizing effect of the NaOH/NH4OH post-treatment on the templated mesoporous materials and their photocatalytic activity was investigated. Furthermore, the thermal and mechanical properties of commercially available titanium dioxides such as P25 Evonik (R) and Millenium PC500 (R) were studied. The various photocatalysts were analyzed with N-2-sorption, X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) to obtain information concerning the specific surface area, pore volume, crystal structure, morphology, phase transitions, etc. In general, results show that the NaOH post-treatment leads to an increased control of the crystallization process during calcination resulting in a higher thermal stability, but at the same time diminishes the photocatalytic activity. Mesoporous materials in which pre-synthesized nanoparticles are used as titania source have the best mechanical stability whereas the mechanical stability of the nanotubes is the most limited. At increased temperatures and pressures, the tested commercial titanium dioxides lose their superior photocatalytic activity caused by a decreased accessibility of the active sites. The observed changes in adsorption capacities and photocatalytic activities cannot be assigned to one single phenomenon. In this respect, it shows the need to define a general/standard method to compare different photocatalysts. Furthermore, it is shown that the photocatalytic properties do not necessarily deteriorate under thermal stress, but can be improved due to crystallization, even though the initial material is (partially) destroyed. It is shown that the usefulness of a specific type of photocatalyst strongly depends on the application and the temperature/pressure to which it needs to resist. (C) 2012 Elsevier Inc. All rights reserved.
Notes: [Ribbens, S.; Beyers, E.; Meynen, V.; Cool, P.] Univ Antwerp, Dept Chem, Lab Adsorpt & Catalysis, B-2160 Antwerp, Belgium. [Schellens, K.] Univ Hasselt, Lab Inorgan & Phys Chem, B-3590 Diepenbeek, Belgium. [Mertens, M.] Flemish Inst Technol Res, VITO NV, B-2400 Mol, Belgium. [Ke, X.; Bals, S.; Van Tendeloo, G.] Univ Antwerp, Dept Phys, EMAT, B-2020 Antwerp, Belgium. vera.meynen@ua.ac.be
URI: http://hdl.handle.net/1942/13718
DOI: 10.1016/j.micromeso.2012.01.036
ISI #: 000303625200010
ISSN: 1387-1811
Category: A1
Type: Journal Contribution
Validation: ecoom, 2013
Appears in Collections: Research publications

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