ORIGINAL PAPER Mesoporous and mesostructured TiO 2 coatings for photocatalytic applications Yolanda Castro • Alicia Dura ´n Received: 23 August 2013 / Accepted: 10 December 2013 Ó Springer Science+Business Media New York 2013 Abstract The correlation between the textural properties and the photocatalytic activity of nanocrystalline Titanium dioxide (TiO 2 )-anatase films obtained by sol–gel has been investigated. Mesoporous and mesostructured TiO 2 -anatase films were prepared using different titanium precursors and Pluronic (F127) and polyethylene glycol hexadecyl ether P5884 (Brij58) surfactants via acid catalysis. Ca(NO 3 ) 2 and WCl 6 were incorporated to TiO 2 sols to investigate the effect of the doping on the photocatalytic behaviour. The microstructure and textural properties were characterised by X-ray diffraction, spectral ellipsometry and transmis- sion electronic microscopy. The photocatalytic properties were evaluated in aqueous solution (methyl orange) and in gas phase (trichloroethylene, sulphide acid and methyl- ethyl-ketone) using multilayer films deposited on glass- slides. TiO 2 -B-Brij-58 films exhibited the most efficient photocatalytic activity either in aqueous or gas medium. The Ca doping strongly enhances the photocatalytic activity associated with the reduced recombination of electrons and holes in the catalyst. Keywords TiO 2 -anatase  Sol–gel coatings  Photocatalysis  TCE  H 2 S  MEK  Methyl orange 1 Introduction Titanium dioxide (TiO 2 ) is one of the most interesting materials for applications in water and air purification, because it presents photocatalytic activity able to degrade harmful organic contaminants. Other characteristics such as an excellent optical transparency in the visible and near infrared regions [1], high corrosion resistance [2, 3], chemical stability, and low cost make it a useful material for purification of indoor and office buildings, and indus- tries ambient, covering a wide spectrum of environmental applications including decontamination, purification, and deodorization of air and water [4, 5]. The photocatalytic degradation process is based in the semiconductor activa- tion by UV and/or visible light irradiation with the con- sequent generation of electron–hole pairs. These reactive electron–hole pairs produce highly potent radicals (such as  OH and O 2- ) able to oxidize harmful organic and inor- ganic pollutants. For an effective photo-excitation of TiO 2 semiconductor it is necessary illumination with energy higher than the titania-anatase band gap (E band-gap ), around 3.2 eV, which absorption threshold corresponds to 380 nm [6]. In particular, TiO 2 powders have been commonly used as photocatalyst for water purification [7–9]. However, the post-treatment implicates the separation of the powder catalysts in a slurry system, this being considered a main disadvantage [10]. Currently, the purification of air con- taminants is being explored more and more due to con- tinuous increasing exposure of people to high pollution rates in in-door sites such as hospitals. For this purpose the immobilization of TiO 2 on transparent substrates is one promising alternative compared to the use of powder and bulk materials. Different techniques have been used to obtain TiO 2 films on different substrates, sol–gel process appearing as one of the most suitable methods to produce this type of coatings. Indeed it is especially recommended since TiO 2 easily crystallises as anatase, the most active photocatalytic phase, at rather low temperatures, even at RT [11, 12]. Y. Castro (&)  A. Dura ´n Instituto de Cera ´mica y Vidrio (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid, Spain e-mail: castro@icv.csic.es 123 J Sol-Gel Sci Technol DOI 10.1007/s10971-013-3240-1