Title Page
Contents
ABSTRACT 11
Chapter 1. General Introduction 14
1.1. Synthetic dyes wastewater 14
1.1.1. Classification of synthetic dyes 14
1.1.2. Treatment of synthetic dyes wastewater 17
1.2. Advanced oxidation processes (AOPs) 18
1.2.1. Ultrasonic catalytic degradation technology 19
1.2.2. Photocatalytic degradation technology 21
1.3. Semiconductor Nanomaterials 22
1.3.1. Classification of semiconductors 22
1.3.2. Characteristics of semiconductor nanomaterials 24
1.3.3. Applications of semiconductor nanomaterials 27
1.4. Several synthesis methods of semiconductor nanomaterials as photocatalysts 27
1.4.1. Hydrothermal method 28
1.4.2. Chemical precipitation method 29
1.4.3. Microwave radiation method 30
1.4.4. Chemical vapor deposition (CVD) 30
1.5. Methods for improving photocatalytic activity of semiconductor nanomaterials 30
1.5.1. Combination with carbon nanomaterials 32
1.5.2. Doping 35
1.5.3. Construction of heterojunctions 36
Chapter 2. Preparation of SnO₂-C₆₀ nanocomposites and their application in the photocatalytic degradation of organic dyes 38
2.1. Introduction 38
2.2. Experimental section 39
2.2.1. Materials 39
2.2.2. Preparation of SnO₂ nanoparticles and SnO₂-C₆₀ nanocomposites 39
2.2.3. Characterization 39
2.2.4. Photocatalytic degradation of organic dyes 40
2.3. Results and discussion 40
2.3.1. Characterization of the photocatalysts 40
2.3.2. Photocatalytic performance 45
2.3.3. Kinetics study 49
2.3.4. Enhancement mechanism in photocatalytic performance 50
2.4. Conclusion 51
Chapter 3. Preparation of CdSe-Mn-C₆₀ nanocomposites and their application in the photocatalytic degradation of organic dyes 53
3.1. Introduction 53
3.2. Experimental section 54
3.2.1. Materials 54
3.2.2. Preparation of Mn-doped CdSe nanoparticles and CdSe-Mn-C₆₀ nanocomposites 54
3.2.3. Characterization 55
3.2.4. Photocatalytic degradation of organic dyes 55
3.3. Results and discussion 56
3.3.1. Characterization of the photocatalysts 56
3.3.2. Photocatalytic performance 60
3.3.3. Kinetics study 64
3.3.4. Enhancement mechanism in photocatalytic performance 66
3.4. Conclusion 67
Chapter 4. Preparation of Cu₂O-Cu-Graphene nanocomposites and their application in the photocatalytic degradation of organic dyes 68
4.1. Introduction 68
4.2. Experimental section 69
4.2.1. Materials 69
4.2.2. Preparation of Cu-doped Cu₂O nanoparticles and Cu₂O-Cu-Graphene nanocomposites 70
4.2.3. Characterization 70
4.2.4. Photocatalytic degradation of organic dyes 71
4.3. Results and discussion 72
4.3.1. Characterization of the photocatalysts 72
4.3.2. Photocatalytic performance 77
4.3.3. Kinetics study 81
4.3.4. Enhancement mechanism in photocatalytic performance 82
4.4. Conclusion 83
References 85
Table 1.1. Characteristics and structural formula of methyl orange. 15
Table 1.2. Characteristics and structural formula of orange II. 16
Table 1.3. Characteristics and structural formula of methylene blue. 16
Table 1.4. Characteristics and structural formula of rhodamine B. 17
Table 1.5. Characteristics and structural formula of brilliant green. 17
Table 2.1. Average crystalline sizes at (110) plane of SnO₂ in pure SnO₂ nanoparticles and SnO₂-C₆₀ nanocomposites. 42
Table 2.2. The final photocatalytic degradation efficiencies of SnO₂ nanoparticles and SnO₂-C₆₀ nanocomposites for organic dyes. 49
Table 3.1. Crystalline diameters of CdSe in Mn-doped CdSe nanoparticles and CdSe-Mn-C₆₀ nanocomposites. 58
Table 4.1. Crystalline diameters of each component in Cu-doped Cu₂O nanoparticles and Cu₂O-Cu-Graphene nanocomposites. 74
Table 4.2. The final photocatalytic degradation efficiencies of Cu-doped Cu₂O nanoparticles and Cu₂O-Cu-Graphene nanocomposites for organic dyes. 81
Fig. 1.1. Basic schematic diagram of ultrasonic catalytic degradation. 20
Fig. 1.2. Basic schematic diagram of photocatalytic degradation. 22
Fig. 1.3. Schematic diagram of hydrothermal reactor. 29
Fig. 1.4. The structural schematic diagram of graphene. 33
Fig. 1.5. The structural schematic diagram of fullerene. 34
Fig. 1.6. The structural schematic diagram of carbon nanotube. 35
Fig. 2.1. XRD patterns of (a) SnO₂ nanoparticles and (b) SnO₂-C₆₀ nanocomposites. 42
Fig. 2.2. Comparison SEM images of (a) SnO₂ nanoparticles and (b) SnO₂-C₆₀ nanocomposites. 43
Fig. 2.3. Raman spectra of (a) SnO₂ nanoparticles and (b) SnO₂-C₆₀ nanocomposites. 45
Fig. 2.4. UV-vis spectra of the degradation of (a) MB, (b) MO, and (c) RhB with SnO₂ nanoparticles as photocatalysts under UV lamp illumination at 254 nm. 47
Fig. 2.5. UV-vis spectra of the degradation of (a) MB, (b) MO, and (c) RhB with SnO₂-C₆₀ nanocomposites as photocatalysts under UV lamp illumination at 254 nm. 48
Fig. 2.6. Kinetics studies of the photocatalytic degradation of organic dyes with (a) SnO₂ nanoparticles and (b) SnO₂-C₆₀ nanocomposites as photocatalysts... 50
Fig. 2.7. Enhancement mechanism of SnO₂-C₆₀ nanocomposites in the photocatalytic degradation of organic dyes under 254 nm UV irradiation. 51
Fig. 3.1. XRD patterns of (a) Mn-doped CdSe nanoparticles and (b) CdSe-Mn-C₆₀ nanocomposites. 57
Fig. 3.2. Comparison SEM images of (a) Mn-doped CdSe nanoparticles and (b) CdSe-Mn-C₆₀ nanocomposites. 59
Fig. 3.3. Raman spectra of (a) Mn-doped CdSe nanoparticles and (b) CdSe-Mn-C₆₀ nanocomposites. 60
Fig. 3.4. UV-vis spectra of the degradation of (a) MB, (b) MO, and (c) RhB with Mn-doped CdSe nanoparticles as photocatalysts under UV irradiation at 254 nm. 62
Fig. 3.5. UV-vis spectra of the degradation of (a) MB, (b) MO, and (c) RhB with CdSe-Mn-C₆₀ nanocomposites as photocatalysts under UV irradiation at 254 nm. 64
Fig. 3.6. Kinetics studies of the degradation of (a) MB, (b) MO, and (c) RhB with Mn-doped CdSe nanoparticles and CdSe-Mn-C₆₀ nanocomposites as... 66
Fig. 3.7. Enhancement mechanism of CdSe-Mn-C₆₀ nanocomposites in the photocatalytic degradation of organic dyes under 254 nm UV irradiation. 67
Fig. 4.1. XRD patterns of (a) Cu-doped Cu₂O nanoparticles and (b) Cu₂O-Cu-Graphene nanocomposites. 73
Fig. 4.2. Comparison SEM images of (a) Cu-doped Cu₂O nanoparticles and (b) Cu₂O-Cu-Graphene nanocomposites. 75
Fig. 4.3. Raman spectra of (a) Cu-doped Cu₂O nanoparticles and (b) Cu₂O-Cu-Graphene nanocomposites. 77
Fig. 4.4. UV-vis spectra of the degradation of (a) MB, (b) MO, and (c) RhB with Cu-doped Cu₂O nanoparticles as photocatalysts under UV irradiation at 254 nm. 79
Fig. 4.5. UV-vis spectra of the degradation of (a) MB, (b) MO, and (c) RhB with Cu₂O-Cu-Graphene nanocomposites as photocatalysts under UV irradiation... 80
Fig. 4.6. Kinetics studies of the photocatalytic degradation of organic dyes with (a) Cu-doped Cu₂O nanoparticles and (b) Cu₂O-Cu-Graphene... 82
Fig. 4.7. Enhancement mechanism of Cu₂O-Cu-Graphene nanocomposites in the photocatalytic degradation of organic dyes under 254 nm UV irradiation. 83