| Titre : | Elaboration and characterization of undoped and doped titanium dioxide thin layers by sol gel (spin coating) for photocatalytic applications |
| Auteurs : | Radhia Messemche, Auteur ; Hanane Saidi, Directeur de thèse |
| Type de document : | Monographie imprimée |
| Editeur : | Biskra [Algérie] : Faculté des Sciences Exactes et des Sciences de la Nature et de la Vie, Université Mohamed Khider, 2021 |
| Format : | 1 vol. (135 p.) / ill. en coul., couv. ill. en coul. / 30 cm |
| Langues: | Anglais |
| Mots-clés: | Thin layers,sol-gel,titanium dioxide,photocatalytics,gallium doping,Methylene bleu,structural properties,optical properties,organic pollution |
| Résumé : |
Titanium dioxide thin films were deposited by sol-gel spin coating technique using titanium tetra-isopropoxide, absolute ethanol and acetylacetone as precursor solution, solvent and catalyzer, respectively. The effect of the solution concentration, rotation speed, molar ratio
and gallium doping concentration on the structural, morphological, optical and photocatalytic properties of TiO2 thin films was studied. All films were characterized by multiple techniques such as X-ray diffraction (XRD), UV-Visible spectroscopy, scanning electron microscope (SEM), photoluminescence (PL) spectroscopy and Fourier transform infrared (FTIR) spectroscopy to investigate the physical properties of titanium dioxide films. X-ray diffraction analysis shows that all films are oriented preferentially along to (101) plane. SEM images show that the films are homogenous, uniform and dense with some holes and cracks. The optical transparency of TiO2 films around to 90% in visible range which related to good crystalline state of the films. The direct band gap was varied between 2.99 and 3.6 eV. The photoluminescence analysis revealed mainly three emission peaks (ultraviolet, blue and green) corresponding to the near band edge (NBE) and defect levels (DL) emissions. It found at 0.2 M, the samples have a photocatalytic property with the photodegradation rate reach to 84%. The latter is improved used galuim doping TiO2 which became equal to 95%. Whereas, the photodegradation rate reaches to 94 % at t = 180 min in undoped TiO2 films with molar ratio y = 0.66. The elaborated films (deposited at 4000 rpm) as a photocatalyst to change the water acidity from pH = 4.8 to pH = 7.4 with produce H2 gas. The latter used as a promising fuel for the future that protects the environment from pollution. |
| Sommaire : |
Didication..........................................................................................................................i Acknowledgements………………………………………………………………………………………………ii Contents…………………………………………………………………………………………………………...iii General introduction ...........................................................................................................................1 I.1. Introduction .....................................................................................................................................5 I.2 Thin films…………………………………………………………………………...…………………………..5 I.2.1 Thin films growth process…………………………………...…………………………………………….5 I.3 Titanium dioxide (TiO2)……………………………………………………………………..………………..8 I.3.1 Different phases of titanium dioxide (TiO2)………………………………………………………........8 I.3.2 Surface energies……………………………………………………………………………………..……10 I.3.3 Types defects in TiO2……………………………………………………………………………………..11 I.3.4 Electronic structures of TiO2…………………………………………………………………………….14 I.3.5 Optical properties………………………………………………………………………………………….15 I.3.6 Doping of TiO2……………………………………………………………………………………………...16 I.3.6.1 Gallium properties………………………………………………………………………………………16 I.3.6.2 Gallium doped of TiO2 thin films……………………………….……………………………………..17 I.4 Photocatalytic activity application…………………………………………………………………….…17 I.4.1 Why was titanium dioxide chosen?..............................................................................................17 I.4.2 Photocatalysis mechanism………………………………………………………………………………17 I.4.3 The role of hydroxyl radicals…………………………………………………………………………….20 I.4.4 Factors affecting photocatalysis degradation rate (PDE)…………………………………………..20 I.4.5 Effect of the allotropic phase of TiO2 on photocatalytic activity…………………………………..21 I.4.6 Photocatalytic activity of doped TiO2…………………………………………………………………..21 I.5 Organic pollution…………………………………………………………………………………………….22 I.5.1 Water Pollution Due to Organic Dyes…………………………………………………………………..22 I.5.2 Degradation of Dye Pollutants…………………………………………………………………………..23 I.5.3 Dangers of organic pollutants…………………………………………………………………………...24 I.5.4 Methylene blue properties………………………………………………………………………………..24iv I.6 Photocatalysis parameters………………………………………………………………………….……..25 I.6.1 Intensity of absorption (A)………………………………………………………………………………..25 I.6.2.Kinetic constant (K_app )………………………………………………………………………………...27 I.6.3 Photocatalytic degradation rate (PDR)…………………………………………………………………28 II.1. Introduction ...................................................................................................................................30 II.2 Thin films depositions techniques ................................................................................................30 II.3 Sol-Gel method................................................................................................................................31 II.3.1 Sol-gel process ............................................................................................................................31 II.3.2 Reaction mechanisms of the sol-gel method ............................................................................32 II.3.3 Different sol-gel methods............................................................................................................34 II.3.3.1 Spin-coating ................................................................................................................... ……..34 II.3.3.2 Dip-coating……………...………………………………………………………………………………35 II.4 Characterization methods………………………………………………………………………………...35 II.4.1 X rays diffraction (XRD)………………………………………………………………………………….35 II.4.2 Scanning electron microscope (SEM)…………………………………………….…………………..37 II.4.3. Energy dispersive X-ray spectroscopy (EDS or EDX)……………………………………………...38 II.4.4 Photoluminescence spectroscopy…………………………………………………………………….39 II.4.5 Fourier Transform Infrared (FTIR)……….……………………………………………………………..40 II.4.6 Raman spectroscopy…………………………...………………………………………………………..41 II.4.7 UV-Visible spectroscopy………………………………………………………………………………...42 II.4.7.1 Film thickness |
| En ligne : | http://thesis.univ-biskra.dz/5395/1/Messemeche%20Radhia%20Doctorat%20thesis.pdf |
Disponibilité (1)
| Cote | Support | Localisation | Statut |
|---|---|---|---|
| TPHY/106 | Théses de doctorat | bibliothèque sciences exactes | Consultable |
