ANNOTATION
INTRODUCTION 6
1. Literature review 8
1.1 Preparation of films based on TiO2 and CeO2 by the sol-gel method 8
1.1.1 Sol-gel method of TiO2 film preparation 9
1.1.2 Sol-gel method of CeO2 film preparation 12
1.1.3 Sol-gel method of TiO2-CeO2 film preparation 15
1.2 Phase composition of samples 19
1.3 Optical properties of TiO2-CeO2 films 23
1.4 Applications and functional properties of TiO2-CeO2 films 27
2. Methodological part 31
2.1 Preparation of TiO2-CeO2 thin film by sol-gel method 31
2.1.1 Preparation of film forming solution 31
2.1.2 Preparation of TiO2-CeO2 thin film 31
2.2 Methods for studying the composition and process of FFS formation 32
2.2.1 Viscosity determination method 32
2.2.2 IR spectroscopy 32
2.3 Methods for studying the processes of formation of oxide systems 33
2.3.1 Thermal analysis 33
2.3.2 X-ray phase analysis method 33
2.4 Methods for studying the optical properties of films 34
2.4.1 UV spectrometry 34
3. Experimental part 36
3.1 The process of formation and composition of film-forming solution based on TBT with addition and without of cerium(III) nitrate 36
3.2 The process of thermal destruction of film-forming solution 40
3.3 Optical properties of TiO2 and TiO2-CeO2 film 47
CONCLUSION 52
REFERENCE 53
ATTACHMENT A 61
Currently, there is an increasing demand for oxide thin film in various fields of industry and modern technology. TiO2-CeO2 thin films are used for detection of uric acid [1], self-cleaning glass [2], gas sensors [3], photocatalysts (insert full liter in the photo section) and antibacterial coatings [4], purification of various organic pollutants in water [5-17], etc.
Thin film materials based on titanium (IV) and cerium (IV) oxides have attracted great interest due to the catalytic activity of TiO2 and the easy conversion of cerium between reduced and oxidized forms [18]. Titanium dioxide is characterized by a large band gap of 3.2 eV, which allows the use of photocatalysts based on it only under the influence of UV irradiation. Photocatalysts are also characterized by a fast rate of charge carrier recombination. The introduction of cerium dioxide makes it possible to reduce the band gap, which allows materials to operate under the influence of visible radiation. In addition, the use of photocatalysts in the form of a thin film of TiO2-CeO2 simplifies the technology of photocatalytic purification of real water objects, compared to TiO2-CeO2 powder, and solves the problem of the difficulty of extracting powdered photocatalyst from the solution being purified.
The known physical methods for producing thin film TiO2-CeO2 oxide systems require the use of expensive equipment and consume energy. Among the chemical methods for preparing TiO2-CeO2 thin films, the sol-gel synthesis method is the most widely used [2, 3, 4, 19], which is energy-saving, simple, and does not require the use of expensive equipment. In the proposed methods, the stability of sols is achieved by varying and strictly controlling the pH of the medium and introducing polymerizing agents into their composition. Therefore, it is necessary to develop new compositions of film-forming solutions. Questions related to the influence of cerium dioxide content on the optical properties of the resulting materials also remain relevant, since the data presented in the literature are ambiguous.
The aim of work was to establish the effect of cerium dioxide additives on the optical properties of titanium dioxide thin-film materials obtained from a film-forming solution by the sol-gel method.
To achieve this goal, the following tasks were defined:
- preparation of film-forming solutions (FFS) based on butanol- tetrabutoxytitanium (TBT), butanol-TBT-cerium(III) nitrate and studying the processes occurring in the solution by infrared spectroscopy and viscometry;
- analysis of the thermal destruction process of dry FFS by thermal and X-ray phases analysis;
- obtaining thin film materials on glass substrates from FFSs by dip coating;
- determination of the composition and structure of the film through X-ray phase analysis;
- determination of optical properties of thin film materials by UV-visible spectroscopy.
The methods used include: infrared spectroscopy and viscometry, thermal analysis, X-ray phase analysis, UV-visible spectroscopy and other methods.
The instruments used include but are not limited to VPZh-2 capillary viscometer, Cary 630 FTIR spectrophotometer, simultaneous thermal analyzer STA 449 C Jupiter, Rigaku Mini Flex 600 diffractometer (CuKa radiation), and PE-5400UF spectrophotometer.
1. TiO2-CeO2 thin film materials can be prepared from film-forming solution (FFS) based on Ce(NOs)3’6H2O, tetrabutoxytitanium and butanol by sol-gel method.
2. Precursor for oxide film preparation are sol in which the bond [-Ti-O-Ti], [-O-Ce-], [-Ti-O-Ce-] exist.
3. Thermal destruction of dried at 60 °C Ti(OC4H9)4-Ce(NO3>-C4H9OH FFS on the surface of glass substrate occurs at temperature not less than 550 C. At this temperature, titanium dioxide with the structure of anatase and cerium dioxide of the amorphous phase is formed.
4. The resulting films of pure TiO2 and TiO2-CeO2 have a high transmittance in the visible region of the spectrum (more than 60% at 1 > 500 nm). The addition of cerium oxide leads to an increase in the absorption of films in the region close to the ultraviolet range (1 = 320-450 nm), and also leads to a decrease in their band gap to 2.8 eV compared to TiO2 films (3.3 eV). The prepared TiO2-CeO2 films can be recommended for further research as photocatalysts.
