Al doping effect on the morphological, structural and photocatalytic properties of TiO2 thin layers (original) (raw)
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Surface and Interface Analysis, 2020
The metal ion-doped (Fe 3+ , Co 2+ , Ni 2+ and Ag +) TiO 2 nanocrystalline thin films were spin-coated on glass substrates. The grazing incidence X-ray diffractometer (GIXRD), SEM, energy-dispersive X-ray Spectroscopy (EDX), Raman, UV-VIS and a fluorescence spectrometer were employed to study the structural, compositional and optical properties of metal-doped TiO 2 films. As revealed by GIXRD, all the metal-doped TiO 2 thin films were found to anatase tetragonal crystal structure. The deposited films were optimized using annealing temperature (550 C) to get high-quality crystalline films with the anatase phase. The thin films with the specific surface area of Fe-, Co-, Ni-and Ag-doped anatase TiO 2 nanocrystals are 152.18, 88.25 96.68 and 178.38 m 2 /g, respectively, which has been calculated by GIXRD results. Optical transmittance spectra were used to determine the thickness, band gap energy and refractive index of metal-doped TiO 2 thin films. The characteristic vibrational Raman modes also revealed that the films were found to be anatase phase. The intensity of luminescence emission decreases with the doping of metal ions. Metal-doped TiO 2 films exhibit strong photocatalytic performance than undoped TiO 2 films. The degradation efficiencies typically increase with the different dopants for the visible-light degradation of methylene blue (MB) and methyl orange (MO). Moreover, the photocatalytic activity (PCA) of silver ion-doped titania thin film is found to be better than that of Fe 3+-, Co 2+-, and Ni 2+-doped TiO 2 films.
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.
Journal of the Korean Physical Society
Mono, co-and tri-doped TiO2 thin films with the transition metals (vanadium and/or chrominium) and a nonmetal (nitrogen) have been fabricated by sol-gel method. X-ray diffraction results clearly reveal anatase crystal structure for all obtained samples and doping with any dopants doesn't change the anatase phase of TiO2. Compared to TiO2, three types of doped TiO2 thin films exhibit a red-shift in the absorption edge and have much better photocatalytic properties for methylene blue degradation in visible light region. The maximum visible-photocatalytic performance was achieved for tri-doped TiO2 sample. The mechanism for enhancing visible-photocatalytic activity of co-doped and tri-doped TiO2 thin films was also examined.
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.
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...
The effect of annealing on photocatalytic properties of nanostructured titanium dioxide thin films
Dyes and Pigments, 2007
The photocatalytic degradation of a non-biodegradable azo dye called (C.I. Direct 80, Red Sulphonyl 3BL) was investigated using TiO 2 thin films in aqueous solution under irradiation of a mercury lamp Philips (UV-C) light source. The effect of operational parameters, i.e., annealing temperature of thin film, substrate nature on which TiO 2 films were deposited, film thickness, pH of the solution, dye concentration, and irradiation time on the degradation rate of azo dye aqueous solutions was examined. Results show that the employment of efficient photocatalyst and the selection of optimal operational parameters lead to complete decolorization. The best conditions for maximum photocatalytic degradation were found to be pH 1 at 5 ppm concentration of dye over TiO 2 thin films deposited on glass substrate coated with indium-tin oxide having 350 nm thicknesses annealed at 550 C. The samples are all in the complete anatase phase and the particle size is in nanometer scale which is confirmed by XRD pattern analysis.
Enhancing the photocatalytic activity of TiO 2 nanocrystalline thin film by doping with SiO 2
Chemical Engineering Journal, 2011
Nanocrystalline films of TiO 2 :XSiO 2 (X = mol percent) with high photocatalytic activity was prepared on glass substrate via the sol-gel method. The films were subjected to high temperature treatment at 500 • C for growing TiO 2 crystals. Energy Dispersive X-ray Spectroscopy (EDS) was used to indicate the elements in the films. The EDS result showed that besides Ti, O and Si elements, there were small amounts of Ca, Na and Mg. X-ray diffraction (XRD) analysis indicated that TiO 2 :XSiO 2 films contain only anatase phase. Scanning electron microscopy (SEM) was used to study the films surface morphology. The TiO 2 :SiO 2 films that were contacted with methyl orange (MO) in the aqueous solution (10 mg L −1 ) and irradiated with UV showed a high photocatalytic activity. UV spectrophotometry technique was used to monitor the degradation of methyl orange (MO) by the reduction of main absorbance peak at 464 nm. The results showed that complete degradation was achieved after 1.5 h.
Journal of Experimental Nanoscience, 2012
This study reports on the synthesis, characterisation and environmental applications of immobilised Titanium dioxide (TiO 2) as photocatalyst. Nanostructured thin films have been prepared on glass substrates using a layer-by-layer dip-coating method. The crystalline phase and surface morphology of the thin films were investigated by X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM), respectively. The XRD results show that the TiO 2 thin films crystallise in anatase phase and we have found that the thin films consist of titanium dioxide nanocrystals. SEM shows that the nanoparticles are sintered together to form a compact structure and TiO 2 particles coated with silver nanoclusters were observed. Ag-coated TiO 2 films demonstrated photocatalysis performance when irradiated, and the Ag carrier further showed an electron-scavenging ability to mitigate electron-hole pair recombination, which can improve the photocatalytic efficiency. With the oxidisation and electron-scavenging ability of Ag and the photocatalysis ability of TiO 2 , Ag-coated TiO 2 can decolour methyl orange (MO) more than bare TiO 2. It is a new approach to form Ag-coated TiO 2 nanoparticles with a simple system and nontoxic materials. The high photocatalytic effect of Ag-coated TiO 2 nanoparticles on pollutant (MO) suggests that it may have a promising future for water and wastewater treatments.
Effect of substrate on surface morphology and photocatalysis of large-scale TiO2 films
Applied Surface Science, 2013
Nanostructured TiO 2 films were prepared on a variety of substrates, including acid frosted soda-lime glass, acid frosted soda-lime glass pre-coated with a SiO 2 barrier layer, commercial glazed ceramic tile and 6061 aluminum alloy. For each substrate, the phase and microstructure of the films were determined to be exclusively anatase. However, the growth of the TiO 2 crystallites, the film morphology and thickness varied substantially with substrate. Thermal stress, resulting from the difference in the coefficient of thermal expansion between the substrates and the films, contributed to the formation and propagation of cracks. This was most clearly observed on the films deposited on SiO 2 barrier layer and aluminum. The photocatalytic activity of the TiO 2 films deposited on glass with and without SiO 2 barrier layer, ceramic, and aluminum was studied via UV decolorization of methyl orange in aqueous solution. Complete degradation rapidly occurred on the TiO 2 /glass and TiO 2 /SiO 2 barrier layer films, but not with the ceramic or metal substrates. It appears that the photocatalytic activity of the films deposited on aluminum and ceramic substrates was affected by the quantity and the size of the anatase crystallites. The aluminum substrate promoted the formation of TiO 2 films with the largest anatase crystallite size, exhibiting a cracked morphology, where as the ceramic substrate resulted in the formation of TiO 2 films with large crystallite size in an island morphology.
Photocatalysis and hydrophilicity of doped TiO2 thin films
Journal of Colloid and Interface Science, 2003
TiO 2 thin films were prepared using the dip-coating method with a polymeric sol including additives such as Al, W, and Al + W to examine two major properties: photocatalysis and hydrophilicity. W-doped films showed the best photocatalytic efficiency, while Al-doped film was poorer than undoped samples. However, good hydrophilicity in terms of saturation contact angle and surface conversion rate was found in Al-and (Al + W)-mixed-doped films. It was found that deep electron-hole traps and high surface acidity of W-doped TiO 2 thin film were the major factors in high photocatalytic efficiency. In addition, low surface acidities of Al-and (Al + W)-doped films provided better hydrophilicity than W-doped ones. However, the amount of [Ti 3+ ] point defects on the surface was another major factor, probably the most important, in getting the best hydrophilicity. Conclusively, it seemed that many parts of the photocatalysis mechanism depend more on bulk-related properties than do those of hydrophilicity, which can be defined as an interfacial (surface) or near-surface-restricted process.