Synthesis of CNT-titania-silica nanocomposite thin films: the effect of heat treatment on photocatalytic activity

Download
2014
Kırbaş, Tuğçe
In this study, CNT-TiO2-SiO2 nanocomposites were synthesized by sol-gel process and the thin films over glass substrates were fabricated by dip coating method. The effects of CNT addition, heat treatment temperature and atmospheres on the structure and photocatalytic properties were examined. The thin films were prepared with and without carbon nanotubes and the heat treatment was carried out at different temperatures in the range of 300-600oC under air and nitrogen atmosphere. Characterization of the samples was performed by thermal analysis, XRD, SEM&EDS, elemental carbon analysis, XPS and UV-Vis spectroscopy. Thermal analysis indicated that the oxidation temperature of carbon nanotubes was reduced significantly by the presence of TiO2-SiO2 and considerable amount of carbon is oxidized under nitrogen atmosphere. XRD studies showed that the crystallinity is enhanced by heat treatment temperature. The SEM images revealed that CNTs were successfully incorporated in thin film structure. Elemental carbon analysis was performed to obtain the residual carbon amount after heat treatment. The results were consistent with thermal analysis and showed that quantity of carbon is decreasing with increasing temperature under both air and nitrogen atmospheres. UV-Vis Spectroscopy indicated the photoabsorption edge of thin films is at UV region which is in agreement with titania. XPS studies showed that the reduction of Ti4+ to Ti3+ sites during heat treatment under nitrogen flow and these oxygen vacancies over the surface are known as effective sites for photocatalysis. The photocatalytic activity tests were performed by monitoring the degradation of metyhylene blue under UV irradiation in the presence of the thin film. The CNT-added samples have higher photocatalytic activity than the TiO2-SiO2 sample. And also higher heat treatment temperatures favor the photocatalytic activity until the sintering. The most photocatalycally active sample is found as the CNT-TiO2-SiO2 thin film that was heat treated at 500oC under air atmosphere.

Suggestions

Synthesis and characterization of copper phthalocyanine deposited mica titania pigment
Topuz, Berna Burcu; Gündüz, Güngör; Department of Polymer Science and Technology (2010)
In the present work, anatase and rutile titanium dioxide (TiO2) coated lustrous mica pigments were prepared by heterogeneous nucleation method. Anatase-rutile phase transformation of the TiO2 on mica substrate was achieved by coating very thin layers of tin (IV) oxide on mica surfaces prior to TiO2 deposition. Muscovite mica, which was used in the experiments was sieved, pre-treated with sodium bicarbonate and decantated before coating process. The surface morphology of mica titania pigments and anatase-rut...
SYNTHESIS OF TiO2 NANOSTRUCTURES VIA HYDROTHERMAL METHOD
Bilgin, Nursev; Agartan, Lutfi; PARK, JONGEE; Öztürk, Abdullah (2014-10-16)
Titania (TiO2) nanostructures were produced via hydrothermal method using amorphous TiO2 powders synthesized by the sol-gel precipitation process. The hydrothermal system was isolated from the environment and hydrothermal reactions were allowed to execute at 130 degrees C for 36 h at autogeneous pressure, and at a stirring rate of 250 rpm. Scanning electron microscopy (SEM) analysis revealed that TiO2 nanofibers formed instead of nanotubes upon utilization of amorphous TiO2 precursor. After hydrothermal syn...
Preparation of lead free BZT-BCT thin films by chemical solution deposition and their characterization
Çeltikçi, Barış; Özenbaş, Ahmet Macit; Department of Metallurgical and Materials Engineering (2012)
In the presented thesis, lead-free Ba(Ti0.8Zr0.2)O3-(Ba0.7Ca0.3)TiO3 (BZT-BCT) thin films were deposited on Pt/TiO2/SiO2/Si substrates using chemical solution deposition method and then the effect of process parameters were investigated to obtain optimum parameters of these lead-free thin films. The phase was selected near to the morphotropic phase boundary (MPH) to increase the number of polarization directions where rhombohedral and tetragonal phases exist together. In this study, the effect of sintering ...
Characterization and preparation of thin films and homogeneously precipitated Pb(Zr,Ti)O3 powders Homojen olarak çökelti̇lmi̇ş Pb(Zr,Ti)O3 tozlarin ve i̇nce fi̇lmleri̇n hazirlanmasi ve karakteri̇zasyonu
Özenbaş, Ahmet Macit (1999-12-01)
In this study, ferroelectric Pb(Zr,Ti)O3 powders and thin films were prepared from metal chlorides using sol-gel processing method. For powders; homogeneous precipitation from aqueous solution and for films; dip coating just before precipitation was applied in the presence of urea, [(NH2)2CO]. Characterization of the films and powders were carried out primarily by XRD and SEM/EDX. Both the films and powders were stoichiometric and completely crystallized into perovskite phase after annealing for 5 hours at ...
Synthesis and charaterization of single hollow opaque polymer pigments
Karakaya, Ekin; Gündüz, Güngör; Maviş, Bora; Department of Chemical Engineering (2013)
In the present work opaque polymer pigments with single hollow structure were synthesized by osmotic swelling method. The hollow pigment is composed of an outer shell and an inner void space which can be filled with air or water. The osmotic swelling process involves synthesizing of a core polymer containing carboxylic acid group on the backbone, and encapsulating it with another polymer which functions as shell. The swelling of the polymer is provided by neutralization of the core with a base. Methyl metha...
Citation Formats
T. Kırbaş, “Synthesis of CNT-titania-silica nanocomposite thin films: the effect of heat treatment on photocatalytic activity,” M.S. - Master of Science, Middle East Technical University, 2014.