Thin films of titanium dioxide modified with MoO 3 nanostructures for photocatalytic applications (original) (raw)

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...

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.

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...

Optimization and comparative evaluation of optical and photocatalytic properties of TiO2 thin films prepared via sol–gel method

Journal of Saudi Chemical Society, 2015

TiO 2 thin films were fabricated with optimization of the synthesis parameters for efficient photocatalysis. The films were sculptured from gels obtained from Ti(O i Pr) 4 and Ti(OBu s) 4 via spin coating at different rotation speed ranging from 1000 rpm to 3000 rpm. Thicknesses of the films were in the range of %112-160 nm. The X-ray diffractograms showed a phase transformation from anatase to rutile along with an increase in average crystallite size from 11 nm to 18 nm with a decrease in thickness of the films. Refractive index (n) values of the films were in the range of 2.50-3.45 while extinction coefficient (k) values ranged from 0.090 to 0.860. These films were transparent with high transmittance (T 6 95%) in the visible region. The optical band gaps for films were calculated to be in the range of 3.00-3.95 eV. Photocatalytic degradations of methylene blue by the fabricated TiO 2 thin films have also been investigated.

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.

Nanostructured low crystallized titanium dioxide thin films with good photocatalytic activity

Powder Technology, 2010

Transparent TiO2 thin films were deposited on soda lime glass at different substrate temperatures by a simple and reproducible spray pyrolysis technique from aqueous peroxo-polytitanic acid. Both the as-prepared and annealed films (3 h thermal treatment in air at 500 °C) were characterized by AFM, SEM, TEM, XRD, FT-IR and UV–visible spectroscopy. The as-prepared films present predominant low crystallized structure, low porosity, high surface roughness and grain agglomerates while the annealed films exhibit slightly better polycrystalline structure of brookite phase. The as-deposited TiO2 films prepared at low substrate temperatures (280 °C) show the best photocatalytic activity, against methylene-blue, due principally to their small grain size and high surface area.In this work, transparent and low crystallized TiO2 thin films were deposited on soda lime glass at different substrate temperature by spray pyrolysis technique from aqueous peroxo-polytitanic acid. The as-prepared films (at 280 °C substrate temperature) have exhibited good photocatalytic activity against aqueous methylene-blue solution. TiO2 particle size measured by TEM for this material was around 7 nm.

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.

Synergistic effect of doping with nitrogen and molybdenum on the photocatalytic properties of thin titania films

Vacuum, 2015

Doping of titania with metal and non-metal elements provides a simple and efficient pathway to significant enhancement of photocatalytic properties. In this work titania thin films codoped with molybdenum and nitrogen were prepared by reactive magnetron sputtering. Additionally, coatings doped only with nitrogen were prepared under identical deposition conditions for comparison purposes. Coatings were annealed at 873 K in air and analysed by Raman spectroscopy, XRD and XPS. Photocatalytic properties of the coatings were evaluated on the basis of the photodegradation rate of methylene blue dye under UV, fluorescent and visible light. It was found that the photocatalytic activity of co-doped samples was significantly higher than that of N-doped coatings. Unlike N-doped titania films, co-doped coatings exhibited high photocatalytic activity under the fluorescent light source and noticeable activity under visible light. The possible mechanism for the enhancement of the photocatalytic activity of Mo-N co-doped titania coatings is discussed.

MoO 3 in Self-Organized TiO 2 Nanotubes for Enhanced Photocatalytic Activity

Chemistry - An Asian Journal, 2010

Self-organized nanostructures (nanotubes and nanopores) consisting of TiO 2 -MoO 3 were grown on Ti-Mo substrates with different Mo contents (7 wt % Mo, 20 wt % Mo, and 35 wt % Mo) by electrochemical anodization. The photocatalytic activity of these oxide layers was compared with TiO 2 nanotubes. The results show clearly that MoO 3 doping of approx. 7 wt % strongly enhances the achievable photodegradation ability of titania nanotubes. The findings bear considerable significance for pollutant degradation and other photocatalytic applications of TiO 2 .

Morphology and photocatalytic activity of highly oriented mixed phase titanium dioxide thin films

Surface and Coatings Technology, 2011

Thin TiO 2 films on quartz substrates were prepared by spin coating of undoped and metal-ion-doped Sol-Gel precursors. These films were characterised by Scanning Electron Microscopy, Laser Raman Microspectroscopy, X-ray Diffraction and UV-Vis Transmission. The photocatalytic performances of the films were assessed by the photo-degradation of methylene-blue in aqueous solution under UV irradiation. Films exhibited a high degree of orientation and a thermal stabilization of the anatase phase as a result of substrate effects. In the absence of dopants, the rutile phase formed as parallel bands in the anatase which broadened as the transformation progressed. TiO 2 films doped or co-doped with transition metals exhibited the formation of rutile in segregated clusters at temperatures under~800°C as a result of increased levels of oxygen vacancies. Photocatalytic activity of the films synthesised in this work was low as likely a result of poor TiO 2 surface contact with dye molecules in the solution. The presence of transition metal dopants appears detrimental to photocatalytic activity while the performance of mixed phase films was not observed to differ significantly from single phase material.