| Titre : | Synthesis and characterization of mixed oxides applicable as catalysts and photocatalysts using solar energy |
| Auteurs : | Djamel Eddine Mazouzi, Auteur ; Djani Fayçel, Auteur |
| Type de document : | Thése doctorat |
| Editeur : | Biskra [Algérie] : Faculté des Sciences Exactes et des Sciences de la Nature et de la Vie, Université Mohamed Khider |
| Format : | 1VOL.(48p) / ill.couv.ill.en coul / 30cm |
| Langues: | Anglais |
| Langues originales: | Anglais |
| Résumé : |
This thesis investigates BiFeO3/Bi2O3 composites as a potential solution for environmental remediation and clean energy generation. It details the autocombustion synthesis of BiFeO3, Bi2O3, and BiFeO3/Bi2O3 composites with varying Bi excesses, followed by comprehensive characterization using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), and UV-visible spectroscopy. Notably, the characterization reveals a lower band gap and porous morphology for the BiFeO3/Bi2O3 composite compared to the individual oxides. Which demonstrate the composite's superior performance in both photocatalytic degradation of organic pollutants and hydrogen gas generation through sodium borohydride methanolysis. Overall, this work highlights the promise of BiFeO3/Bi2O3 composites as efficient and reusable catalysts, paving the way for a more sustainable future. |
| Sommaire : |
General introduction ………………………..………………………….……………….…2 CHAPTER I : BIBLIOGRAPHIC STUDY I.1. Materials…………………………………………………....…...……....…5 I.1.1. Mixed oxides…….…………………………………………………...………………5 I.1.1.1. BiFeO3 ………………………………………….……….……...........5 I.1.2. Simple oxides ………...…………………………………………….……...........6 I.1.2.1.Bi2O3 ………………….………………….……………………………6 I.1.3. Composites. ……………………………………….…… ........…………………7 I.2. Synthesis methods ………………………………………………………..………..8 I.2.1. Sol-gel ………….………………………………………………………....……….8 I.2.2. Co-precipetation synthesis …………………………………..…………....…..8 I.2.3. Solid state synthesis ………………………………..……………………………..8 I.2.4. Green synthesis ……………………………………………………….….……...…...9 I.2.5. Microwave assisted synthesis ………………….…………………..…..…………9 I.2.6. Sunlight driven ingnition synthesis ………………...…………………..…....…9 I.2.7. Hydrothermal. ……………………….…………………..……...…………..………10 I.2.8. Autocombustion …………………...............................…………………..…………10 I.3. Application. ……………………………………….…….………………..…….……..…12 I.3.1. Photocatalysis ………………………….…………………………………..……..…..12 I.3.1.1. Photocatalytic degradation of toxic organic compounds…………………………...……………………………….………..…….13 I.3.1.2. Photocatalysis with nitrobenzene………..……………………..…….………..…….……………………14 I.3.2. Catalysis ……………………...…………………………...…………………..………16 I.3.2.1. Mixed oxides catalysts ……..…………………………..….….……..16 I.3.3. Hydrogen production ………………………………….…...…………..17 I.3.3.1. Catalytic hydrogen prodution …………………………...………………18 I.3.3.2. Sodium borohydride hydrolysis ……………….…………………...……19 I.3.3.3. Sodium borohydride methanolysis ……………….…...…..……….……19 I.3.3.4. Hydrogen production by photocatalysis ………...…...……………..….20 CHAPTER II : SYNTHESIS, CHARACTERIZATION TECHNIQUES AND PHOTOCATALYTIC & CATALYTIC PROCESSES DESCRIPTION II.1 Autocombustion synthesis ….…………...…………..……………..……34 II.1.1. Synthesis of oxides….…………...………..……..…………..…………35 II.2. Characterization methods ………………………...…………..….…………..35 II.2.1. X-ray diffraction ………………………..……….………………….………..35 II.2.1.1. Introduction ………...…...…………………………………………..……35 II.2.1.2. Principle ……………………………………………...………………36 II.2.1.3. Apparatus used …………………………...……………………….…37 II.2.2. Scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) …………………………………………………………...37 II.2.2.1. Introduction ………...…...……………………………………………..….37 II.2.2.2. Principle ………………………………………………...……………38 II.2.2.3. Apparatus used …………………………...………………………….38 II.2.3. Fourier transform infra red (FTIR) spectroscopy………………………..……………………………………...…….……..39 II.2.3.1. Introduction ………...…...……………………………………………..….39 II.2.3.2. Principle ………………………………………………...……………39 II.2.3.3. Apparatus used …………………………...………………………….40 II.2.4. X-ray photoelectron spectroscopy (XPS) .…………………...…………..41 II.2.4.1. Introduction ………...…...…………………………………………..…….41 II.2.4.2. Principle …………………………………...…………...……………41 II.2.4.3. Apparatus used ………………………...…………………………….42 II.2.5. UV-Vis spectroscopy….………………………………………….…………..43 II.2.5.1. Introduction ………...…...…………………………………………...……43 II.2.5.2. Principle …………………………………...…………...……………44 II.2.5.3. Apparatus used …………………………...………………………….44 II.3. Photocatalytic experiments ….………………………………………………..45 II.4. Catalytic tests ….……………………………………………………….………..45 II.4.1. Catalytic hydrogen generation ….………………..………………………..46 II.4.1.1. Catalyst amount effect ……………………………………………….46 II.4.1.2. Substrate effect ……………………………………...……………….46 II.4.1.3. Temperature effect …………………………………….………….….46 II.4.1.4. Reusability ……………………………………………………..…….46 CHAPITRE III : AUTOCOMBUSTION SYNTHESIS OF O3/Bi2O3,AND ITS PROPERTIES III.1. Introduction ….…………………………………….....………………………..51 III.2. Autocombustion synthesis of the samples…….....………………………..51 III.2.1. Preparation of BiFeO3 …….....……………………………………...……..51 III.2.2. Preparation of Bi2O3 …….....……………………………………..………..52 III.2.3. Preparation of BiFeO3/ Bi2O3 …….....…………………………..………..53 III.3. Characterization of oxides …….....……………………..……………….…..53 III.3.1. X-ray diffraction analysis …….....……………………….………………..53 III.3.1.1. XRD of the synthesized BiFeO3 …………………….………..……..53 III.3.1.2. XRD of the synthesized Bi2O3 …………………….………..……….54 III.3.1.3. XRD of the synthesized composites with the excess of Bismuth .….55 III.3.2. XPS measurments of bare oxides and BB5 composite ……..………..57 III.3.2.1. XPS of bare oxides ………………………………………………………57 III.3.2.2. XPS of the synthesized BB5 composite ………………………..………59 III.3.3. SEM-EDS analysis of oxides …………………………………………………….…60 III.3.3.1. SEM-EDS of BiFeO3 ……………………………….……………………60 III.3.3.2. SEM-EDS of Bi2O3 ……………………………….………...……………61 III.3.3.2. SEM-EDS of BB5 composite ………………………………...…………62 III.3.4. Fourier transform infra red spectroscopy analysis …………..……….…63 III.3.5. UV-Visible measurments ……………………………………...……..……….…64 III.3.5.1. Optical band gap of BiFeO3 ……………………………………………65 III.3.5.2. Optical band gap of Bi2O3 ………………...……………………………66 III.3.5.3. Optical band gap of BiFeO3/ Bi2O3 ……………………………………66 III.3.5.4. Comparison between optical band gap of the three compounds ……..67 III.4. Conclusion …………………………………………………………...……..……….…67 CHAPTER IV : PHOTOCATALYTIC AND CATALYTIC PERFORMANCE OF BiFeO3/Bi2O3 SYSTEM IV.1. Introduction ……………………………………….…………………….73 IV.2. Photocatalytic tests ……………………………...……………………...73 IV.2.1. Photocatalytic efficiency of BiFeO3 ……………………………..…...73 IV.2.1.1. Under lamp illumination …………………………………………….....73 IV.2.1.2. Under sunlight irradiation……………………..……………………..…74 IV.2.2. Photocatalytic efficiency of Bi2O3 ………………………………..…..75 IV.2.2.1. Under lamp illumination …………………………………………….…75 IV.2.2.2. Under sunlight irradiation……………………..…………………….....75 IV.2.3. Photocatalytic efficiency of BiFeO3/ Bi2O3 ………………………......76 IV.2.3.1. Under lamp illumination …………………………………………….…76 IV.2.3.2. Under sunlight irradiation……………………..……………………..…76 IV.2.4. Photocatalytic efficiency comparison ……………………………......77 IV.2.5. Kinetic study of NB degradation ……………………………………..77 IV.2.6. Mineralization measurments of NB photodegradation ………...…..80 IV.2.7. Unveiling the elimination mechanism ……...……………………......80 IV.2.8. Recyclability of BiFeO3/ Bi2O3 …………………………...……...…..82 IV.3. Catalytic tests………………… …………………………...………...…..84 IV.3.1. Oxide amount efficiency for the catalytic reaction…………..….…..84 IV.3.2. Catalytic efficiency between oxides……………………….………….85 IV.3.3. The substrate effect on hydrogen evolution…………………………85 IV.3.4. The effect of temperature on the catalytic reaction…………….…...86 IV.3.5. Reusability of the BiFeO3/Bi2O3 catalyst…………………………….87 IV.4. Conclusion……………………………………………………………….88 General conclusion ………….…………………………….……….………….93 List of figures Figure 1: Global market for photocatalysts production……….………………………………2 Figure I.1: A schematic illustrating the methodologies employed in the sy |
| Type de document : | Thése doctorat |
Disponibilité (1)
| Cote | Support | Localisation | Statut |
|---|---|---|---|
| TCH/125 | Théses de doctorat | bibliothèque sciences exactes | Consultable |
