Photocatalytic Semiconductors (eBook)

Preface 6
Acknowledgments 10
Contents 12
Chapter 1: Semiconducting Materials 14
1.1 Fundamentals 14
1.1.1 Band Structures 14
1.1.2 Intrinsic and Extrinsic Semiconductors 16
1.1.3 Band Edge Positions and Band Gaps 17
1.1.4 Semiconductors for Photocatalysis 19
1.1.5 Mechanism of the Photocatalytic Process 19
1.2 Photocatalytic Semiconductors: Classification 22
1.2.1 Metal Oxides 22
1.2.2 Chalcogenides: Other than Oxides 24
1.2.3 Ternary Compounds 24
1.2.4 Quaternary Compounds 25
1.3 Advantages and Disadvantages in the Use of Titanium Dioxide (TiO2) as Photocatalytic Semiconductor 26
1.3.1 Visible Light Active TiO2-NM (NM=Nonmetal) 30
1.3.1.1 Nitrogen-Doped TiO2 31
1.3.1.2 Carbon-Doped Titanium Dioxide Materials 37
1.3.1.3 Fluorine-Doped Titanium Dioxide Materials 42
1.3.1.4 Boron-Doped Titanium Dioxide Materials 44
Concluding Remarks 46
References 46
Chapter 2: New Visible-Light Active Semiconductors 54
2.1 Ion-Doped Semiconductors (M+=Transition Metal Ion) 55
2.2 Nonmetal-Doped Materials 58
2.3 Dye-Sensitized Semiconductor 65
2.4 Coupled Semiconductors 68
2.5 Nanostructured Semiconductors: Effect of Size and Composition 71
Concluding Remarks 74
References 75
Chapter 3: Synthesis Methods for Photocatalytic Materials 81
3.1 Sol-Gel Process 81
3.2 Hydrothermal Method 83
3.3 Solvothermal Technique 86
3.4 Direct Oxidation Method 88
3.5 Sonochemical Method 90
3.6 Microwave Method 92
3.7 Chemical Vapor Deposition 96
3.8 Physical Vapor Deposition (PVD) 101
3.9 Electrochemical Deposition 104
Concluding Remarks 107
References 108
Chapter 4: Physicochemical Characterization of Photocatalytic Materials 115
4.1 Elemental Composition 115
4.1.1 Ion Beam Methods 116
4.1.1.1 Rutherford Backscattering Spectroscopy, RBS 116
4.1.1.2 Elastic Recoil Detection Analysis, ERDA 117
4.1.1.3 Particle-Induced X-Ray Emission or Proton-Induced X-Ray Emission PIXE 117
4.1.1.4 Secondary Ion Mass Spectrometry, SIMS 118
4.1.2 Electron Beam Methods 119
4.1.2.1 X-Ray Emission Spectroscopy, XES 120
4.1.2.2 Electron Energy Loss Spectroscopy, EELS 121
4.1.2.3 Auger Electron Spectroscopy, AES 124
4.1.3 X-Ray Beam Methods 125
4.1.3.1 X-Ray Photoelectron Spectroscopy, XPS 125
4.1.3.2 X-Ray Absorption Spectroscopy, XAS 126
4.1.4 Examples 127
4.2 Structure and Topography 129
4.2.1 Structure 129
4.2.1.1 X-Ray Diffraction, XRD 129
4.2.1.2 Transmission Electron Microscopy, TEM 132
4.2.2 Surface Topography 133
4.2.2.1 Contact Techniques 134
4.2.2.2 Non-contact Techniques 135
4.2.3 Examples 136
4.3 Surface Area and Porosity 138
4.3.1 Gas Adsorption 138
4.3.2 Mercury Porosimetry 140
4.3.3 Dynamic Light Scattering 140
4.3.4 Examples 141
4.4 Vibrational Spectroscopies 142
4.4.1 Fourier Transform Infrared Spectroscopy, FTIR 144
4.4.2 Raman Spectroscopy 144
4.4.3 Examples 145
4.5 Optical Properties 146
4.5.1 Transmission and Reflection 149
4.5.2 Diffuse Reflectance 150
4.5.3 Spectroscopic Ellipsometry 152
4.5.4 Photoluminescence (PL) Spectroscopy 157
4.5.5 Other Methods 159
4.5.6 Examples 159
Concluding Remarks 160
References 161
Chapter 5: Electrochemical Characterization of Photocatalytic Materials 166
5.1 Characterization of Thermodynamic Properties in the Semiconductor-Electrolyte Interface Using Electrochemical Techniques 167
5.1.1 The Double Layer at Semiconductor 167
5.1.2 The Flat-Band Potential 169
5.1.3 Light Pulse Techniques 172
5.1.4 Electrochemical Determination of the VFb of Particles in Suspension 173
5.1.5 The Band Gap Energy 174
5.1.6 Fermi Level 175
5.2 Characterization of Kinetic Properties in the Semiconductor-Electrolyte Interface Using Electrochemical Techniques 177
5.2.1 Separation of Transport, Charge Storage, and Reaction Elements in Nanostructured Oxide Semiconductor Electrodes 177
5.2.2 Interparticle Electron Transport Through Semiconductor Nanostructured Films 178
5.3 Determination of Photocatalytic Efficiency of Semiconductor-Electrolyte Interface Using Electrochemical Techniques 178
5.3.1 Monochromatic Quantum Efficiency 178
5.3.2 Photochemical Thermodynamic Efficiency Factor (PTEF) 180
5.3.3 Relative Photonic Efficiency (xir) 184
5.3.4 Quantum Yield (Phi) 184
Concluding Remarks 193
References 193
Chapter 6: Semiconductor Materials for Photocatalytic Oxidation of Organic Pollutants in Wastewater 197
6.1 Introduction 198
6.2 Photocatalytic Degradation of Organic Compounds in the Presence of TiO2 Catalyst 198
6.3 Degradation of Organic Pollutants in the Presence of TiO2 or ZnO Doped with Metals 206
6.4 TiO2 Doped with Nonmetals for the Degradation of Organic Pollutants 214
6.5 Coupling Two Semiconductor Systems for the Removal of Organic Pollutants 219
6.6 Photocatalytic Degradation of Organic Pollutants in the Presence of Other Semiconductors 223
Concluding Remarks 231
References 232
Chapter 7: Application of Semiconductor Photocatalytic Materials for the Removal of Inorganic Compounds from Wastewater 239
7.1 Cyanides 239
7.2 Removal of Heavy Metals and Metalloids 244
7.2.1 Arsenic 245
7.2.2 Chromium 250
7.2.2.1 Photocatalytic Reduction of Cr(VI) with TiO2-Based Semiconductors 250
7.2.2.2 Photocatalytic Reduction of Cr(VI) with ZnO and Other Semiconductors 257
Concluding Remarks 259
References 260
Chapter 8: Photocatalytic Materials in Water Disinfection 265
8.1 Process for Water Disinfection 266
8.1.1 Electrochemical Disinfection Processes 267
8.1.2 Photocatalytic Disinfection Processes 268
8.2 Photocatalytic Reactor: Configurations for Water Disinfection 271
8.2.1 State of the Photocatalyst 271
8.2.2 Visible Light-Absorbing Semiconductors 273
8.2.3 Reactor Design and Engineering of Photocatalytic Units 274
8.3 Efficiency of Photocatalytic Materials 277
8.3.1 Photocatalytic Thermodynamic Efficiency Factor (PTEF) for Oxidation-Reduction 277
8.3.2 Inactivation Apparent Quantum Yield (IQY) 278
8.4 Based Materials Used for Water Disinfection 279
Concluding Remarks 283
References 283
Chapter 9: Future and Perspectives for Photocatalytic Materials in Environmental Photocatalysis 289
9.1 Economic Aspects in the Production and Application of Photocatalytic Materials 290
9.2 Toxicological and Environmental Impacts of the Use of Photocatalytic Materials 292
Concluding Remarks 294
References 294
Index 296