Article (Scientific journals)
Doped sol–gel films vs. powders TiO2: On the positive effect induced by the presence of a substrate
Léonard, Géraldine; Malengreaux, Charline; Melotte, Quentin et al.
2016In Journal of Environmental Chemical Engineering, 4, p. 449-459
Peer reviewed
 

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Keywords :
Thin film; TiO2–SiO2; Powder; Sol–gel; Photocatalysis; TiO2; Ag nanoparticle
Abstract :
[en] SiO2 and Ag–SiO2 doped TiO2 films and powders have been produced using a controlled sol–gel process. The dopant has been introduced using an alkoxysilane-functionalized ligand, with or without complexed silver ions. The influence of dopants on physico-chemical properties of the catalysts is studied by XRD, TEM–EDX, DRUV–vis analyses in the case of powders, while GIXRD, XPS, profilometry, UV–vis absorption analyses have been used for thin films. The photocatalytic activity has been evaluated from the degradation of methylene blue under UV-A light in the presence of the different catalysts over a period of 24 h. The detailed comparison between powders and films highlights a surprising positive effect in the case of films due to the presence of the substrate. In the case of photocatalytic powders, the presence of SiO2 or Ag–SiO2 into the TiO2 matrix has a detrimental effect on the photocatalytic activity while the opposite tendency is observed in the case of films, with best activities obtained with Ag–SiO2 doping. Different factors, in particular crystallinity modification between powders and films, have been studied to explain these opposite behaviors. In the case of powders, crystallization is hindered by SiO2 and Ag particles incorporation into the TiO2 matrix, leading to a decrease of the photocatalytic activity. In the case of thin films, probably because of the presence of a substrate, crystallization is not influenced by the presence of SiO2 and Ag particles. Therefore, the latter ones can fully play their role of electron traps leading to an enhanced photocatalytic activity.
Disciplines :
Materials science & engineering
Chemical engineering
Author, co-author :
Léonard, Géraldine ;  Université de Liège > Department of Chemical Engineering > Génie chimique - Nanomatériaux et interfaces
Malengreaux, Charline
Melotte, Quentin
Lambert, Stéphanie  ;  Université de Liège > Department of Chemical Engineering > Department of Chemical Engineering
Bruneel, Els;  Université de Gand
Van Driessche, Isabel;  Université de Gand
Heinrichs, Benoît ;  Université de Liège > Department of Chemical Engineering > Génie chimique - Nanomatériaux et interfaces
Language :
English
Title :
Doped sol–gel films vs. powders TiO2: On the positive effect induced by the presence of a substrate
Publication date :
2016
Journal title :
Journal of Environmental Chemical Engineering
ISSN :
2213-2929
eISSN :
2213-3437
Publisher :
Elsevier Science
Volume :
4
Pages :
449-459
Peer reviewed :
Peer reviewed
Available on ORBi :
since 05 January 2016

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