Optimized deposition of TiO2 thin films produced by a non-aqueous sol–gel method and quantification of their photocatalytic activity

Abstract

TiO 2 thin films have been produced by a dip-coating process using a non-aqueous sol-gel method. This study investigated the influence of the operating variables such as nature of the substrate, sol concentration, withdrawing speed of the dip-coater and number of layers on the physico-chemical properties of the films using XRD, GIXRD, UV-Vis spectroscopy, profilometry, spectroscopic ellipsometry and SEM. Photocatalytic activity of the films was * Corresponding author. The performances of the catalysts were compared through the reaction rate constants determined using an apparent first-order kinetic model adjusted on the experimental data.This study showed that the photocatalytic activity and the reaction rate constant depend on the film thickness through the synthesis and dipping variable, with an optimum thickness of 80 nm being observed. An optimized transparent film exhibiting a high adhesion, a well crystallized TiO 2 -anatase phase, a good photocatalytic activity and a reaction rate constant k equal to 0.126 h -1 was obtained using a simple process. The specific photocatalytic activity of this film was higher to the one measured for TiO 2 powders in previous works.

Recent developments in TiO2 as n- and p-type transparent semiconductors: synthesis, modification, properties, and energy-related applications

“…The sol-gel process has distinct advantages over other techniques, including excellent compositional control, homogeneity at the molecular level due to the mixing of liquid precursors, and lower crystallization temperature [123][124][125][126]. Moreover, the microstructure (i.e., the pore size, pore volume, and surface area) of films can be tailored by controlling the processing parameters such as the ratio of the components and temperature [127].…”

Doping TiO2 films with carbon nanotubes to simultaneously optimise antistatic, photocatalytic and superhydrophilic properties

“…Alkaline-free glass (75 9 25 9 0.7 mm) was used as supports to avoid the presence of sodium [22,25]. In the case of aqueous synthesis, the glass surface has to be pretreated to ensure the adherence of the sol.…”

“…In the present study, MWCNT-doped TiO 2 films have been produced from sol-gel chemistry by dipping glass slides in either aqueous or alcoholic sols [21,22]. One motivation to choose the sol-gel process is the possibility of producing large film surfaces, quickly and at reasonable costs, which is a sine qua non condition for the development of easy-to-clean/self-cleaning coatings [3,6,7,10,[19][20][21].…”

“…Contrary to aqueous synthesis which allows the production of crystalline anatase at low temperature [23], alcoholic synthesis requires calcination to transform amorphous TiO 2 into anatase. Because TiO 2 films are calcined at around 500°C for anatase crystallisation [21,22] and the MWCNT combustion temperature is around 450°C [2,7,10,[18][19][20], various calcination temperatures of alcoholic samples are tested in this study to optimise TiO 2 crystallisation without degrading MWCNTs.…”

Photocatalytic Activity of TiO2 Nanofibers with Doped La Prepared by Electrospinning Method

“…10 La 3+ as one of usual rare-earth ions is doped to TiO 2 in order to improve its photocatalytic activity. At present, one-dimensional nanofibers with large specific surface area and length-diameter ratio have been prepared by a various of methods, such as hydrolysis method, 11 hydrothermal process, 12 sol-gel method 13 and electrospinning technique. [14][15] Among these ways, electrospinning technique is a simple, versatile and easy method for fabricating the continuous nanofibers, which forms different morphologies and constructions.…”