Synthesis and characterization of mixed oxides: experimental and theoretical study of their photocatalytic activity / Sarra Bouriachi

Public ISBD Titre : Synthesis and characterization of mixed oxides: experimental and theoretical study of their photocatalytic activity Type de document : document électronique Auteurs : Sarra Bouriachi, Auteur ; Ibrahim el Khallil Haddad, Directeur de thèse Editeur : Sétif:UFA1 Année de publication : 2024 Importance : 1 vol (112 f.) Langues : Anglais (eng) Catégories : Thèses & Mémoires:Physique Mots-clés : LaFeO3 Nanopores Adsorption Photocatalysis Kinetic models DFT Index. décimale : 530 - Physique Résumé : In this study, LaFeO3 powders with crucial catalytic and photocatalytic performance were successfully prepared through the sol-gel method using chloride and ni trate salts. The influence of the used precursor on the crystallinity, morphology, specific surface area, and optical properties was investigated. TGA and XRD patterns confirmed the formation of the LaFeO3 orthorhombic perovskite phase (Pnma, #62). SEM images highlighted a significant effect of the precursor type on the surface morphology of the synthesized nanoparticles. The obtained band gap varies between 2.19 - 2.27 eV. The kinetic and isotherm adsorption studies revealed that the adsorption of MB molecules on LaFeO3 nanoparticles fitted well with the pseudo-second-order and Freundlich models. Moreover, the thermodynamic study demonstrated that the adsorption of MB on the LaFeO3 samples is spontaneous, exothermic, and more favorable at low temperatures while the magnitude of enthalpy changes energies suggested a physisorption. Hence, LaFeO3 samples prepared with chloride salts are expected to show high photodegradation efficiency of MB dye. In addition, our study was completed by the theoretical investigation, using DFT within GGA+U, of the Bulk and surface properties of LaFeO3. A perfect agreement is found between the experimental results and the theoretical ones. Note de contenu : Sommaire Chapter I: Literature Review I.1 Organic Dyes 8 I.2 Wastewater Treatment Methods 9 I.2.1 Adsorption 10 I.2.1.1 Types of Adsorption 11 1.2.2 Photocatalysis 11 I.2.2.1 Photocatalysis Mechanism 12 I.2.2.2 Types of Photocatalysis 13 I.3 Perovskite Type Oxide 14 I.3.1 Structure Distortion 15 I.3.2 LaFeO3 Perovskite 16 I.3.2.1 Crystal Structure 16 I.3.2.2 Magnetic and Electronic Structure 17 I.3.2.3 Surface Studies on LaFeO3 19 References 21 Chapter II: Experimental Techniques II.1 Sol-gel process 27 II.1.1 Basic Reactions in the Sol-Gel Process 27 II.1.2 Factors Influencing Sol-Gel Process 28 II.2 Characterization Techniques 29 II.2.1 X-Ray Diffraction (XRD) 30 II.2.2 Thermogravimetric Analysis (TGA) 31 II.2.3 Scanning Electron Microscopy (SEM) 33 II.2.4 Brunauer-Emmett-Teller Analysis (BET) 34 II.2.5 Fourier Transform Infrared spectroscopy (FTIR) 35 II.2.6 UV-Visible Spectroscopy 36 References 39 Chapter III: Theoretical Methods III.1 The Schrodinger Equation 42 III.2 Hartree-Fock Approximation 43 III.3 Density Functional Theory 43 III.3.1 Hohenberg-Kohn Theorem 44 III.3.2 The Kohn-Sham Method 44 III.3.3 Exchange-Correlation Functional 45 III.3.3.1 The Local Density Approximation (LDA) 46 III.3.3.2 Generalized Gradient Approximation (GGA) 46 III.3.4 DFT+U 47 III.3.4.1 Hubbard Parameter 47 III.3.4.2 Spin Polarization 48 III.3.5 Self-consistent Procedure 48 III.3.6 Plane Waves Approach 49 III.3.7 Pseudopotential Concept 50 III.3.7.1 Norm Conserving Pseudopotential 51 III.3.7.2 Ultrasoft Pseudopotential 52 III.4 DFT Programs 52 III.4.1 Cambridge Sequential Total Energy Package Code (CASTEP) 52 III.4.2 Dmol3 Code 52 References 54 Chapter IV: Synthesis and Characterization of LaFeO3 Perovskite IV.1 Experimental Procedure 57 IV.1.1 Chemicals 57 IV.1.2 Synthesis of LaFeO3 Based on Nitrate Salts 57 IV.1.3 Synthesis of LaFeO3 Based on Chloride Salts 58 IV.2 Results and Discussion 59 IV.2.1 Thermal Analysis (TGA and DTG) 59 IV.2.2 X-Ray Diffraction Analysis 61 IV.2.3 BET Analysis 64 IV.2.4 Powders Morphology and Composition 64 IV.2.5 Optical Properties 68 IV.2.6 FTIR Spectroscopy 69 References 71 Chapter V: Adsorption and Photocatalytic Activities V.1 Experimental Procedure 75 V.1.1 Methylene Blue Preparation 75 V.1.2 Determination of the Optimum Adsorbent Mass 75 V.1.3 Point of Zero Charge (pHPZC) 76 V.1.4 Influence of the Contact Time 76 V.1.5 Adsorption Kinetics 76 V.1.6 Adsorption Isotherm 77 V.1.7 Adsorption Thermodynamics 78 V.1.8 Photocatalytic Study 78 V.2 Results and Discussion 79 V.2.1 Determination of the Optimum Adsorbent Mass 79 V.2.2 pHPZC Determination 79 V.2.3 Effect of the Contact Time 80 V.2.4 Adsorption Kinetics 81 V.2.5 Adsorption Isotherm 84 V.2.6 Adsorption Thermodynamics 85 V.2.7 Photocatalytic Activity Study 86 References 91 Chapter VI: DFT Calculation of LaFeO3 Properties and MB Adsorption VI.1 Computational Details 95 VI.1.1 Computational Method for Bulk LaFeO3 95 VI.1.2 Computational Method for LaFeO3 Surface 96 VI.2 Results and Discussions 97 VI.2.1 Structural Properties 97 VI.2.2 Electronic and Magnetic Properties 98 VI.2.3 Surface Optimization 102 VI.2.4 Optimization of the Adsorbate 103 VI.2.5 Methylene Blue Adsorption on LaFeO3 Surface 104 References 107 Côte titre : Dph/0310 Synthesis and characterization of mixed oxides: experimental and theoretical study of their photocatalytic activity [document électronique] / Sarra Bouriachi, Auteur ; Ibrahim el Khallil Haddad, Directeur de thèse . - [S.l.] : Sétif:UFA1, 2024 . - 1 vol (112 f.). Langues : Anglais (eng) Catégories : Thèses & Mémoires:Physique Mots-clés : LaFeO3 Nanopores Adsorption Photocatalysis Kinetic models DFT Index. décimale : 530 - Physique Résumé : In this study, LaFeO3 powders with crucial catalytic and photocatalytic performance were successfully prepared through the sol-gel method using chloride and ni trate salts. The influence of the used precursor on the crystallinity, morphology, specific surface area, and optical properties was investigated. TGA and XRD patterns confirmed the formation of the LaFeO3 orthorhombic perovskite phase (Pnma, #62). SEM images highlighted a significant effect of the precursor type on the surface morphology of the synthesized nanoparticles. The obtained band gap varies between 2.19 - 2.27 eV. The kinetic and isotherm adsorption studies revealed that the adsorption of MB molecules on LaFeO3 nanoparticles fitted well with the pseudo-second-order and Freundlich models. Moreover, the thermodynamic study demonstrated that the adsorption of MB on the LaFeO3 samples is spontaneous, exothermic, and more favorable at low temperatures while the magnitude of enthalpy changes energies suggested a physisorption. Hence, LaFeO3 samples prepared with chloride salts are expected to show high photodegradation efficiency of MB dye. In addition, our study was completed by the theoretical investigation, using DFT within GGA+U, of the Bulk and surface properties of LaFeO3. A perfect agreement is found between the experimental results and the theoretical ones. Note de contenu : Sommaire Chapter I: Literature Review I.1 Organic Dyes 8 I.2 Wastewater Treatment Methods 9 I.2.1 Adsorption 10 I.2.1.1 Types of Adsorption 11 1.2.2 Photocatalysis 11 I.2.2.1 Photocatalysis Mechanism 12 I.2.2.2 Types of Photocatalysis 13 I.3 Perovskite Type Oxide 14 I.3.1 Structure Distortion 15 I.3.2 LaFeO3 Perovskite 16 I.3.2.1 Crystal Structure 16 I.3.2.2 Magnetic and Electronic Structure 17 I.3.2.3 Surface Studies on LaFeO3 19 References 21 Chapter II: Experimental Techniques II.1 Sol-gel process 27 II.1.1 Basic Reactions in the Sol-Gel Process 27 II.1.2 Factors Influencing Sol-Gel Process 28 II.2 Characterization Techniques 29 II.2.1 X-Ray Diffraction (XRD) 30 II.2.2 Thermogravimetric Analysis (TGA) 31 II.2.3 Scanning Electron Microscopy (SEM) 33 II.2.4 Brunauer-Emmett-Teller Analysis (BET) 34 II.2.5 Fourier Transform Infrared spectroscopy (FTIR) 35 II.2.6 UV-Visible Spectroscopy 36 References 39 Chapter III: Theoretical Methods III.1 The Schrodinger Equation 42 III.2 Hartree-Fock Approximation 43 III.3 Density Functional Theory 43 III.3.1 Hohenberg-Kohn Theorem 44 III.3.2 The Kohn-Sham Method 44 III.3.3 Exchange-Correlation Functional 45 III.3.3.1 The Local Density Approximation (LDA) 46 III.3.3.2 Generalized Gradient Approximation (GGA) 46 III.3.4 DFT+U 47 III.3.4.1 Hubbard Parameter 47 III.3.4.2 Spin Polarization 48 III.3.5 Self-consistent Procedure 48 III.3.6 Plane Waves Approach 49 III.3.7 Pseudopotential Concept 50 III.3.7.1 Norm Conserving Pseudopotential 51 III.3.7.2 Ultrasoft Pseudopotential 52 III.4 DFT Programs 52 III.4.1 Cambridge Sequential Total Energy Package Code (CASTEP) 52 III.4.2 Dmol3 Code 52 References 54 Chapter IV: Synthesis and Characterization of LaFeO3 Perovskite IV.1 Experimental Procedure 57 IV.1.1 Chemicals 57 IV.1.2 Synthesis of LaFeO3 Based on Nitrate Salts 57 IV.1.3 Synthesis of LaFeO3 Based on Chloride Salts 58 IV.2 Results and Discussion 59 IV.2.1 Thermal Analysis (TGA and DTG) 59 IV.2.2 X-Ray Diffraction Analysis 61 IV.2.3 BET Analysis 64 IV.2.4 Powders Morphology and Composition 64 IV.2.5 Optical Properties 68 IV.2.6 FTIR Spectroscopy 69 References 71 Chapter V: Adsorption and Photocatalytic Activities V.1 Experimental Procedure 75 V.1.1 Methylene Blue Preparation 75 V.1.2 Determination of the Optimum Adsorbent Mass 75 V.1.3 Point of Zero Charge (pHPZC) 76 V.1.4 Influence of the Contact Time 76 V.1.5 Adsorption Kinetics 76 V.1.6 Adsorption Isotherm 77 V.1.7 Adsorption Thermodynamics 78 V.1.8 Photocatalytic Study 78 V.2 Results and Discussion 79 V.2.1 Determination of the Optimum Adsorbent Mass 79 V.2.2 pHPZC Determination 79 V.2.3 Effect of the Contact Time 80 V.2.4 Adsorption Kinetics 81 V.2.5 Adsorption Isotherm 84 V.2.6 Adsorption Thermodynamics 85 V.2.7 Photocatalytic Activity Study 86 References 91 Chapter VI: DFT Calculation of LaFeO3 Properties and MB Adsorption VI.1 Computational Details 95 VI.1.1 Computational Method for Bulk LaFeO3 95 VI.1.2 Computational Method for LaFeO3 Surface 96 VI.2 Results and Discussions 97 VI.2.1 Structural Properties 97 VI.2.2 Electronic and Magnetic Properties 98 VI.2.3 Surface Optimization 102 VI.2.4 Optimization of the Adsorbate 103 VI.2.5 Methylene Blue Adsorption on LaFeO3 Surface 104 References 107 Côte titre : Dph/0310

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
Dph/0310	Dph/0310	Thèse	Bibliothéque des sciences	Anglais	Disponible Disponible

---

1 (1 - 1 / 1)