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

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.


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 ...
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...
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 of alpha-Fe2O3/TiO2 heterogeneous composites by the sol-gel process and their photocatalytic activity
Bouziani, Asmae; PARK, JONGEE; Öztürk, Abdullah (Elsevier BV, 2020-09-01)
alpha-Fe2O3/TiO2 heterogeneous composites were synthesized by the sol-gel process to increase the photocatalytic activity of TiO2. The structural, morphological, and optical characteristics of the composites were determined by X-ray diffraction, scanning electron microscope, and UV-vis diffuse reflectance spectroscopy. Results revealed that the incorporation of alpha-Fe2O3 to TiO2 widened the visible light absorption ability of TiO2. It was realized that the calcination temperature plays a crucial role in m...
Characterization of TiO2 thin films prepared by sol-gel processing
Özenbaş, Ahmet Macit (2004-01-01)
In this work, TiO2 thin films were prepared by using sol-gel processing on soda-lime glass and silicon substrates. Precursor solutions for TiO2 films were prepared by using the proper amounts of titaniumtetraisopropoxide, diethanolamine and ethanol. The thickness of the TiO2 films was adjusted by repeating the spin coating cycle before the final heat treatment. Finally, various amounts of polyethylene glycol (PEG) were added to the above solution to observe its effect on the film morphology. The electrical ...
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.