Study of physical and photocatalytic properties of titanium dioxide thin films prepared from complex precursors by chemical vapour deposition (original) (raw)

Titanium dioxide thin films: the effect of the preparation method in their photocatalytic properties

Journal of Molecular Catalysis A-chemical, 2005

Titanium dioxide thin films were deposited by DC reactive magnetron sputtering and spray pyrolysis methods on glass and glass coated with fluorine tin oxide (FTO). The films were characterized by X-ray diffraction, scanning and transmission electron microscopy, atomic force microscopy and UV–vis spectroscopy. The influence of a reactive atmosphere: a 50/50 Ar–O2 mixture on TiO2 thin films deposited by sputtering has been studied following the evolution of surface and structural properties and has been correlated, when possible, with photocatalytic properties under UV illumination. Also transparent TiO2 thin films have been prepared by spray pyrolysis using a low concentration of titanium precursor and different substrates temperatures. At higher substrate temperatures the films were polycrystalline in anatase phase; at lower substrate temperatures the films presented amorphous configuration. The best photocatalytic activity was found for films deposited by spray pyrolysis at Ts = 450 °C and for those deposited by magnetron sputtering those deposited at 16 mTorr gave the higher photodegradation rates.The behavior of photodegradation of methylene blue on TiO2 thin films when illuminated with UV radiation can be observed in the graphic. For films deposited by magnetron sputtering the variation is followed for pressure increasing in the sputtering chamber. For films deposited by spray pyrolysis the influence of substrate temperature on the photocatalytic activity of TiO2 thin films can be followed from the graphic. The best results are obtained in films deposited at 16 mTorr and with Ts = 400 °C, respectively.

TiO2 thin film synthesis from complex precursors by CVD, its physical and photocatalytic properties

International Journal of Photoenergy, 2003

Photocatalytic TiO 2 films on glass and quartz plates were obtained by the chemical vapour deposition using Ti(dpm) 2 (Opr i ) 2 complex compound (CC-CVD method) in a standard vacuum apparatus at 1.2-2.0 × 10 −4 mbar. The substrate temperature was stabilised in the range of 450-600 • C. The growth rate varied from several nanometres to several dozen of nanometres per minute. Structural information on TiO 2 thin films was obtained from synchrotron radiation experiments. High-resolution grazing incidence X-ray diffraction (GIXRD) experiments were performed at the high-resolution powder diffractometer at the DESY/HASYLAB beamline B2 (Hamburg, Germany). Thin films deposited on either single-crystal Si wafers or on amorphous quartz substrates were analysed. The photocatalytic activity of the TiO 2 thin films was studied using a photocatalytic reactor. The fungicide Fenarimol was chosen as chemical indicator and its degradation kinetics was followed by High-Performance Liquid Chromatography (HPLC). V. G. Besserguenev et al.

Characterization and photocatalytic activities of nanosized titanium dioxide thin films

2011

Thin films of titanium dioxide with high surface area are prepared by sol-gel dip-coating technique. In this regards, Titania nano sols with high photocatalytic activity were prepared by dissolving titanium alkoxide in alcohol and water under acidic conditions. Photocatalytic activities of titanium dioxide thin films were measured in the presence of methylene blue. Microstructure and photocatalytic activity of the films, nanopowders and titanium dioxide sols were investigated using X-ray diffraction, scanning electron microscopy, specific surface area, zeta sizer and ultraviolet-visible spectrometry techniques. Particle size analysis of sols showed that the mean particle sizes were 15 to 128 nm. X-ray diffraction analyses revealed that anatase crystal structure was produced with crystallite size below 11 nm. Increasing mass percent of anatase phase and specific surface area, enhance the photocatalytic activity. Scanning electron microscopy images showed that the addition of methylce...

Effect of the Titanium Isopropoxide:Acetylacetone Molar Ratio on the Photocatalytic Activity of TiO2 Thin Films

Molecules

TiO2 thin films with different titanium isopropoxide (TTIP):acetylacetone (AcacH) molar ratios in solution were prepared by the chemical spray pyrolysis method. The TTIP:AcacH molar ratio in spray solution varied from 1:3 to 1:20. TiO2 films were deposited onto the glass substrates at 350 °C and heat-treated at 500 °C. The morphology, structure, surface chemical composition, and photocatalytic activity of the obtained TiO2 films were investigated. TiO2 films showed a transparency of ca 80% in the visible spectral region and a band gap of ca 3.4 eV irrespective of the TTIP:AcacH molar ratio in the spray solution. TiO2 films consist of the anatase crystalline phase with a mean crystallite size in the range of 30–40 nm. Self-cleaning properties of the films were estimated using the stearic acid (SA) test. A thin layer of 8.8-mM SA solution was spin-coated onto the TiO2 film. The degradation rate of SA as a function of irradiation time was monitored by Fourier-transform infrared spectro...

The Influence of the Precursor Type and of the Substrate on the SPD Deposited TiO2 Photocatalytic Thin Films

Annals of West University of Timisoara - Physics

Photocatalytic degradation of organic pollutants from wastewater using titanium dioxide is recognized as an efficient process. To be feasible, this process needs to be solar- or visible light -activated, but, due to its wide band gap energy, titanium dioxide can only be activated by ultraviolet radiation. In this paper, thin films of titanium dioxide were deposited by Spray Pyrolysis Deposition using organo-metallic (titanium-iso-propoxide) and inorganic (titanium chloride) precursors, as a first step in optimizing the deposition process of titanium dioxide - carbon composite thin films, active in the visible spectral range. The thin films were characterized to outline the differences when using these two precursor solutions, when deposited on Fluorine doped Tin Oxide-glass, regular glass and microscopic glass, in terms of crystallinity (by using X-ray diffraction), elemental composition (using Energy Dispersive X-ray spectrometry), surface morphology (Scanning Electronic Microscopy...

Preparation and characterization of photocatalytic TiO2 films

2005

In the present research, Titanium dioxide (TiO 2) has been synthesized by sol-gel spin coating technique on Corning glass substrates. The sol-gel process can be easily controlled and reproduced. Titanium tetraisopropoxide, isopropanol and deionized water were used as starting materials. This precursor solution was deposited onto Corning glass substrates by spin coating and annealed at 400 and 500 C. Their photocatalytic activity was investigated by examining the degradation (oxidation) of Diuron ® , under UV and solar radiation. In order to compare the photocatalytic activity of TiO 2 and to establish possible correlations between the physicochemical properties of the prepared coatings, these were characterized by UV-Vis spectroscopy and X-ray diffraction (XRD) techniques. X-ray diffraction patterns confirmed TiO 2 anatase phase formation.

Effect of titanium source and sol-gel TiO 2 thin film formation parameters on its morphology and photocatalytic activity

Materials Science - Poland, 2020

TiO 2 thin films with different surface structure have been prepared from alkoxide solutions by the sol-gel method using different cationic precursors and heat treatment techniques. The effect of using titanium isopropoxide as well as titanium butox-ide as a titanium source on the surface structure and photocatalytic activity of the resultant thin films was studied. Significant differences in the rate of hydrolysis and condensation reactions during the sol-gel synthesis were observed for these titanium precursors. This had a direct influence on the morphology of the as-prepared TiO 2 films. Higher quality oxide coatings were obtained from titanium isopropoxide. They were characterized by a smaller grain size, improved surface roughness and uniform coverage of the glass substrate. A beneficial effect of calcination process after each sol application cycle in contrast to single step calcination after all dip-coating cycles was observed. Photocatalytic degradation tests showed that methyl orange was decolorized in the presence of all prepared TiO 2 films by exposing their aqueous solutions to UV light (λ = 254 nm). The highest photocatalytic activity had the TiO 2 layer produced using titanium isopropoxide.

Influence of the structural and surface properties on photocatalytic activity of TiO2:Nd thin films

Polish Journal of Chemical Technology, 2015

Titanium dioxide thin films doped with the same amount of neodymium were prepared using two different magnetron sputtering methods. Thin films of anatase structure were deposited with the aid of Low Pressure Hot Target Magnetron Sputtering, while rutile coatings were manufactured using High Energy Reactive Magnetron Sputtering process. The thin films composition was determined by energy dispersive spectroscopy and the amount of the dopant was equal to 1 at. %. Structural properties were evaluated using transmission electron microscopy and revealed that anatase films had fibrous structure, while rutile had densely packed columnar structure. Atomic force microscopy investigations showed that the surface of both films was homogenous and consisted of nanocrystalline grains. Photocatalytic activity was assessed based on the phenol decomposition. Results showed that both thin films were photocatalytically active, however coating with anatase phase decomposed higher amount of phenol. The t...

Physical properties and photocatalytic efficiencies of TiO2 films prepared by PECVD and sol–gel methods

Materials Research Bulletin, 2004

TiO 2 thin-film photocatalysts coated onto glass were prepared either by plasma enhanced chemical vapour deposition (PECVD) deposition or by a dip-coating process using sol-gel solutions. The influence of the addition of a polymer and of a highly viscous solvent on physical properties (thickness, crystallite size and porosity) of TiO 2 thin films and on their photocatalytic efficiency was evaluated.

Influence of titanium precursor on the photocatalytic properties of TiO 2 sprayed films under visible light

Journal of Physics: Conference Series, 2012

Thin nano-sized TiO 2 films were deposited on aluminum foil substrates by the spray pyrolysis method, using Ti(i-OPr) 4 (TIP) and TiCl 4 (TC) as precursors. The films were characterized by means of X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). According to the XRD patterns the as-deposited films appear to be amorphous. The thermal treatment at 400 o C leads to the formation of anatase nano-crystallites. The XPS analyses showed that the Ti2p broad photoelectron peak of as-deposited TC films indicated a mixture of Ti 3+ and Ti 4+ oxidation states. After treatment at 400 o C the Ti2p peak displays only Ti 4+ oxidation state for both TIP and TC films. The number of hydroxyl groups on the surface is decreased after the thermal treatment. The photocatalytic activity of the films was studied towards degradation of azo dye Reactive Black 5 (RB5) as model wastewater pollutant under visible light illumination. It was found out that the films obtained from TC were more active than those obtained from TIP films. The thermally treated samples are better photocatalysts than those non-treated, because they posses anatase crystalline phase and stoichiometric TiO 2 . The TOC measurements showed minimal concentration of total organic carbon in the dye solution after 180 min of visible light irradiation.