List of Contributors |
Preface |
1 Introduction 1 |
1.1 Background 1 |
1.2 Aim and Outline of This Volume 2 |
1.3 Summary 4 |
1.4 Future Perspectives 4 |
References 5 |
Ⅰ Fundamental Aspects of Photocatalysts |
2 Photoelectrochemical Processes of Semiconductors 9 |
2.1 Semiconductor Electrodes for Solar Energy Conversion 11 |
2.2 Reduction of CO2 at Illuminated Semiconductor Electrodes 15 |
2.3 Photocatalysis 18 |
2.3.1 General Remarks 18 |
2.3.2 Mechanistic Studies 19 |
2.3.3 Low Intensity Illumination 22 |
2.3.4 Applications 24 |
References 26 |
3 Design, Preparation and Characterization of Highly Active Metal Oxide Photocatalysts 29 |
3.1 Introduction 29 |
3.2 Photocatalytic Activity 29 |
3.2.1 Effect of Surface Area on Photocatalytic Activity 30 |
3.2.2 Effect of Electron-hole Recombination on Photocatalytic Activity 32 |
3.2.3 Design of Photocatalysts of High Activity 33 |
3.3 Preparation of Titanium (IV) Oxide Powders 33 |
3.3.1 Sulfate Method 33 |
3.3.2 Chloride Method (Vapor Method) 34 |
3.3.3 Alkoxide Method 34 |
3.3.4 Specific Methods 34 |
3.3.5 Activation of TiO2 Photocatalysts 36 |
3.4 Preparation of Other Photocatalysts 38 |
3.5 Characterization of TiO2 Photocatalysts of Both High Crystallinity and Large Surface Area 38 |
3.5.1 Photocatalytic Activity of HyCOM TiO2 in Aqueous Suspension Systems 38 |
3.5.2 Correlation Between Physical Properties and Photocatalytic Activity of HyCOM TiO2 39 |
3.5.3 Novel Hypothesis for Activity of Photocatalyst 43 |
3.6 Preparation and Characterization of Photocatalytic Thin Films 44 |
3.6.1 Preparation of Photocatalytic TiO2 Thin Films 44 |
3.6.2 Characterization of Photocatalytic Thin Films Prepared from HyCOM TiO2 Powders 45 |
3.7 Summary 47 |
References 47 |
4 Photoelectrochemistry at Semiconductor/Liquid Interfaces 51 |
4.1 Introduction 51 |
4.2 Basic Properties of Semiconductor/Liquid Interface 52 |
4.2.1 Band Bending 52 |
4.2.2 Barrier Height and Flat Band Potential 54 |
4.2.3 Electron Transfer and Corrosion Reactions 57 |
4.3 Photoelectrochemistry at Atomically Well-defined Surfaces 59 |
4.3.1 Atomically Flat H-terminated Si Surfaces 59 |
4.3.2 Selective Exposition of (100) Face on n-TiO2 (Rutile) by Photoetching 62 |
4.4 Photoelectrochemistry at Metal Dot-coated Semiconductors 64 |
4.4.1 Ideal Semiconductor Electrodes 64 |
4.4.2 Metal-loaded TiO2 Electrodes 66 |
References 67 |
5 Photoelectrochemical Reactions at Semiconductor Microparticle 69 |
5.1 Introduction 69 |
5.2 Energy Structure of Semiconductor Microparticle 69 |
5.2.1 Depletion Layer 69 |
5.2.2 Electric Heterogeneity of Surface 71 |
5.2.3 Size Quantization Effect 72 |
5.3 Kinetics at Semiconductor Microparticle 72 |
5.3.1 Recombination Model 73 |
5.3.2 2D Ladder Model 74 |
5.3.3 Effect of Size 76 |
5.4 Observation of Primary Reaction Intermediates 77 |
5.4.1 ESR Analysis for Irradiated TiO2 Particles 78 |
5.4.2 Direct Observation of Intermediate Radicals 81 |
5.4.3 Chemiluminescent Probe for Active Oxygens 83 |
References 85 |
6 New Approaches in Solution-phase Processing of Semiconductor Thin Films 87 |
6.1 Introduction 87 |
6.2 Previous Methods for Solution-phase Deposition of Semiconductor Thin Films 89 |
6.2.1 Chemical Bath Deposition of Metal Sulfide Thin Films 89 |
6.2.2 Electrodeposition of Metal Sulfide Thin Films 90 |
6.2.3 Chemical and Electrochemical Deposition of Metal Oxide Thin Films 92 |
6.3 Electrochemically Induced Chemical Deposition (EICD) of Cds Thin Films 93 |
6.3.1 Idea 93 |
6.3.2 Morphological and Structural Analysis 94 |
6.3.3 Growth Kinetics and Mechanism of EICD Process 95 |
6.3.4 Modification of EICD Process 97 |
6.4 True Electrodeposition of Metal Sulfide Thin Films by Reduction of Thiocyanato Complexes 97 |
6.4.1 Idea 97 |
6.4.2 Thermodynamic Consideration 98 |
6.4.3 Electrochemical Layer-by-layer Growth of CdS Thin Films 98 |
6.4.4 Electrodeposition of Other Metal Sulfides 100 |
6.5 Electrochemical Self-assembly of ZnO/Dye Hybrid Thin Films 100 |
6.5.1 Idea 100 |
6.5.2 Electrochemical Self-assembly of ZnO/Dye Hybrid Structure 102 |
6.5.3 Mechanism of Electrochemical Self-assembly 104 |
6.6 Summary 104 |
References 105 |
Ⅱ Application to Environmental Cleaning |
7 Self-cleaning Properties of TiO2-coated Substrates 109 |
7.1 Introduction 109 |
7.2 Photocatalytic Decomposition 110 |
7.2.1 Air Purifying Effect 110 |
7.2.2 Sterilization Effect 111 |
7.2.3 Anti-fouling Effect 113 |
7.2.4 Photo-induced High Amphiphilicity 114 |
7.3 Conclusions 120 |
References 121 |
8 Cleaning Atmospheric Environment 123 |
8.1 Introduction 123 |
8.2 Photocatalytic Activities of TiO2 124 |
8.2.1 Oxidation of Air Pollutants by Photogenerated Active Oxygen Species 124 |
8.2.2 Photocatalytic Reactions of Volatile Hydrocarbons 125 |
8.2.3 Photocatalytic Reactions of Halogenated Hydrocarbons 136 |
8.2.4 Nitrogen Oxides (Nox) 143 |
8.3 Development of Air Purifying Materials Based on Photocatalyst 147 |
8.3.1 Immobilization of Powder Photocatalysts 147 |
8.3.2 Preparation of Air-purifying Materials 148 |
8.3.3 Performance Characteristics of Air-purifying Materials 149 |
8.4 Application of Photocatalysis to Cleaning of Atmospheric Environment 151 |
8.4.1 Passive Purification of Polluted Air 151 |
8.4.2 Active Air Purification of Closed Space 153 |
8.5 Summary 154 |
References 155 |
9 Water Purification - Degradation of Aqueous Pollutant and Application to Water Treatment 157 |
9.1 Introduction 157 |
9.2 Photocatalytic Characteristics of Titanium Dioxide 157 |
9.3 Photocatalytic Degradation of Pollutant 160 |
9.3.1 Volatile Organohalide Compound 160 |
9.3.2 Pesticides 162 |
9.3.3 Other Organic Compounds 164 |
9.3.4 Environmental Hormones (Endocrine Disruptors) 165 |
9.4 Enhancement of Degradation Rate 166 |
9.4.1 Pt-loading 166 |
9.4.2 Addition of H2O2 167 |
9.4.3 Ozone 169 |
9.4.4 Increase in Adsorption 169 |
9.5 Solar System for Water Treatment 171 |
9.6 Immobilization of TiO2 and Instrumentation 171 |
9.7 Conclusion and Outlook 172 |
References 172 |
10 Second-generation TiO2 Photocatalysts Able to Initiate Reactions Under Visible Light Irradiation 175 |
10.1 Introduction 175 |
10.2 Experimental Section 175 |
10.3 Results and Discussion 176 |
10.4 Conclusion 182 |
References 182 |
Ⅲ Application to Photoenergy Conversion |
11 Photocatalytic Organic Syntheses Using Semiconductor Particles 185 |
11.1 Introduction 185 |
11.2 Principle of Photocatalysis by Semiconductor Particles 186 |
11.3 Photocatalytic Reactions by Semiconductor Suspension 187 |
11.4 Redox Combined Photocatalytic Processes for Nitrogen-containing Substrates 189 |
11.5 Further Development to Stereoselective Organic Synthesis of Nitrogen-containing Compounds 191 |
11.6 Introduction of Oxygen Atoms into Organic Compounds 194 |
11.6.1 Stereospecific Epoxidation of 2-hexene on Photoirradiated TiO2 Powders Using Molecular Oxygen as Oxidant 195 |
11.6.2 Selective Oxidation of Naphthalene by Molecular Oxygen and Water Using TiO2 Photocatalysts 196 |
11.6.3 Photocatalytic Oxygenation: Summary 198 |
11.7 Concluding Remarks 199 |
References 199 |
12 Sonophotocatalysis - Joint System of Sonochemical and Photocatalytic Reactions 203 |
12.1 Introduction - What is Sonophotocatalysis? 203 |
12.2 Utilization of Sonophotocatalytic Reaction 204 |
12.2.1 Sonophotocatalysis of Water 204 |
12.2.2 Sonophotocatalysis of Artificial Seawater 216 |
12.2.3 Sonophotocatalyses of Organic Compounds 219 |
12.3 Conclusion and Future Scopes 220 |
References 221 |
13 Gas-phase Water Photolysis by NaOH-coated Photocatalysts 223 |
13.1 Introduction 223 |
13.2 Water Photolysis by Pt/TiO2 224 |
13.3 Water Photolysis by Metallized Semiconductor Powders 226 |
13.3.1 Gas-phase Water Photolysis by NaOH-coating 226 |
13.3.2 Factors Influencing Yield of Water Photolysis 229 |
13.4 Concluding Remarks 233 |
References 234 |
14 Water Photolysis by TiO2 Particles - Significant Effect of Na2CO3 Addition on Water Splitting 235 |
14.1 Introduction 235 |
14.2 Significant Effect of Carbonate Salt Addition on Water Splitting from Pt/TiO2 Water Suspension 236 |
14.3 Role of Carbonate Salts on Water Splitting and Reaction Mechanism 240 |
14.4 Effective Screening of Active Photocatalysts for Water Splitting Using Na2CO3 Addition Method 242 |
14.5 Solar Hydrogen Production Using Na2CO3 Addition Method 246 |
14.6 Conclusion 248 |
References 248 |
15 Water Photolysis by Titanates with Tunnel Structures 249 |
15.1 Water Photolysis by RuO2/BaTi4O9 with Pentagonal Prism Tunnel Structure 250 |
15.2 Water Photolysis by RuO2/N2Ti6O13 with Rectangular Tunnel Structure 257 |
References 260 |
16 Water Photolysis by Layered Compounds 261 |
16.1 Introduction 261 |
16.2 Layered Oxides of Transition Metals 261 |
16.3 K4Nb6O17 263 |
16.3.1 Structure and Physico-chemical Properties 263 |
16.3.2 Photocatalytic Overall Water Splitting 265 |
16.3.3 Structure of Ni-loaded K4Nb6O17 and Reaction Mechanism 267 |
16.4 Perovskite-related Layered Oxides 268 |
16.5 Summary 276 |
References 276 |
17 Splitting of Water by Combining Two Photocatalytic Reactions via Quinone Redox Couple Dissolved in Oil Phase: Artificial Photosynthesis 279 |
17.1 Introduction 279 |
17.2 Strategy for Water Splitting by Mimicking Photosynthesis 280 |
17.3 Photocatalytic Hydrogen and Oxygen Evolution in Separate Systems 281 |
17.3.1 Photooxidation of Water Using TiO2 Particles 282 |
17.3.2 Photoreduction of Water Using Pt-loaded TiO2 Particles 285 |
17.4 Approaches to Electrochemical and Chemical Combinations of Two Photocatalytic Reactions 286 |
17.5 Splitting of Water by a Combination of Two Photocatalytic Reactions via DDQ/DDHQ 289 |
17.6 Conclusions 291 |
References 291 |
18 Sensitization by Metal Complexes Towards Future Artificial Photosynthesis 293 |
18.1 Introduction 293 |
18.2 Photoinduced Hydrogen Evolution in Homogeneous Four-component Systems 294 |
18.2.1 Photoinduced Hydrogen Evolution with Porphyrin Metal Complexes and Hydrogenase 294 |
18.2.2 Photoinduced Hydrogen Evolution Using Cytochrome c3 as Electron Carrier 296 |
18.2.3 Photoinduced Hydrogen Evolution Using Chemically-modified Chlorophyll 298 |
18.3 Photoinduced Hydrogen Evolution with Viologen-linked orphyrin Metal Complexes 299 |
18.3.1 Photoinduced Hydrogen Evolution with Water-soluble Viologen-linked Cationic Porphyrin Metal Complexes and Hydrogenase 300 |
18.3.2 Photoinduced Hydrogen Evolution with Water-soluble Viologen-linked Anionic Porphyrin and Hydrogenase 302 |
18.4 Other Systems for Hydrogen Evolution Using Natural Photosensitizers 303 |
18.5 Conclusion 306 |
References 306 |
19 Catalyses and Sensitization for Water Reaction Towards Future Artificial Photosynthesis 309 |
19.1 Introduction 309 |
19.2 Design of Artificial Photosynthesis 309 |
19.2.1 Photosynthesis and Energy Cycle on Earth 309 |
19.2.2 Artificial Photosynthesis 311 |
19.3 Molecular Catalysts for Water Reactions and CO2 Reduction 312 |
19.3.1 Catalysis in Water Oxidation 312 |
19.3.2 Catalysis in Proton Reduction 316 |
19.3.3 Catalysis in Carbon Dioxide Reduction 316 |
19.4 Photoexcited State Electron Transfer in Heterogeneous Phases 317 |
19.5 Sensitization of TiO2 Powders and Films in Water 320 |
19.6 Conclusion and Future Prospects 322 |
References 323 |
20 Photoelectric TiO2 Solar Cells 325 |
20.1 Introduction 325 |
20.2 Dye-sensitization of Semiconductors 325 |
20.2.1 History 325 |
20.2.2 Innovative Dye-sensitized Solar Cells 327 |
20.2.3 Fabrication of Dye-sensitized TiO2 Solar Cells 328 |
20.2.4 Characterization of Innovative Dye-sensitized TiO2 Solar Cells 329 |
20.3 Electron-transfer Sensitization on TiO2 330 |
20.3.1 Bonding Structure of Dye on TiO2 Influencing ηei 331 |
20.3.2 Dynamics in Electron Transfer from Photoexcited Dye 2 to TiO2 331 |
20.3.3 Electron Transfer Between Oxidized Dye 2 and I-/I3- Electrolyte 332 |
20.4 Electron Transport in Porous TiO2 Electrodes 333 |
20.4.1 Electron Transport Models for High ηet 334 |
20.4.2 Time-course Analysis 335 |
20.4.3 Frequency Analysis 335 |
20.4.4 Effect of TiO2 Films on Performance of Dye-sensitized Solar Cells 337 |
20.5 Sensitization Dyes 337 |
20.5.1 Ruthenium Polypyridine Complexes 337 |
20.5.2 Other Metal Complexes 339 |
20.5.3 Organic Dyes 340 |
20.5.4 Natural Dyes 342 |
20.6 Recent Research Progress in Dye-sensitized Solar Cells 343 |
20.7 Future Work on Dye-sensitized Solar Cells 344 |
20.8 Concluding Remarks 345 |
References 346 |
Index 349 |