Topics in Current Chemistry Also Available Electronically 7
Aims and Scope 7
Preface 9
Contents 11
Metal Oxide Photoanodes for Water Splitting 13
1 Introduction 14
2 Titanium Dioxide 15
2.1 Nanocrystalline TiO2 Films 15
2.2 Ordered Arrays of TiO2 Nanotubes and Nanorods 22
2.3 TiO2 Doping with Non-Metallic Elements 24
3 Iron Oxide 28
3.1 Doping 30
3.1.1 p-Type Dopants 34
3.1.2 Silicon 35
4 Beyond the Binary Oxide 38
4.1 Binary Metal Oxides 38
4.2 Mixed Metal Oxides 39
4.3 Oxynitrides 41
4.4 Perovskite-Type Semiconductors and Composite Electrodes 44
References 45
Hydrogen Production with Nanostructured and Sensitized Metal Oxides 51
1 Introduction 52
2 Dye Sensitized Photoanodes for Water Oxidation and Hydrogen Evolution 57
3 Highly Ordered Semiconductor Nanostructures Based on TiO2 and TiO2/Metal Chalcogenides 66
3.1 Experimental Conditions for Electrochemical Titania Nanotube Formation 69
3.2 Photoelectrochemical Properties of NT Arrays 72
3.3 Functionalization of Titania Photoelectrodes with Group VI Semiconductors 74
3.4 Methods of Functionalization of Titania Substrates 78
3.5 Bi2S3/TiO2 Photoelectrodes 80
3.6 CdS and CdSe/TiO2 Photoelectrodes 85
3.7 CdTe/TiO2 91
4 Photoelectrodes Based on Anodically Grown WO3 93
4.1 Formation of Anodic WO3 Films by Electrochemical Oxidation of Metallic Tungsten 93
4.2 Photoelectrochemistry 98
References 105
Surface Nanostructures in Photocatalysts for Visible-Light-Driven Water Splitting 107
1 Introduction 108
2 General Role of Cocatalysts in Photocatalytic Water Splitting 110
3 Preparation of a Cocatalyst/Photocatalyst Composite 111
4 Nanoparticulate Mixed Oxides as New Cocatalysts 112
4.1 Motivation for Applying Mixed-Oxides as Cocatalysts 112
4.2 Unique Property of Rh2-yCryO3 Cocatalyst for Photocatalytic Overall Water Splitting 114
4.3 Effect of Gases in the Reaction System on Activity 118
5 Noble Metal/Chromia (Core/Shell) Nanoparticles 120
5.1 Initial Concept for Designing Core/Shell-Structured Nanoparticles as Cocatalysts 120
5.2 Preparation, Characterization, and Functionality 121
5.3 Reason for the Successful Preparation of the Core/Shell Structure 124
5.4 Enhancement of Activity of the Noble Metal/Cr2O3 Core/Shell System by Improving the Dispersion of the Core Component 125
5.5 Application of Cr2O3-Modification to Metal Oxide Core Systems 127
6 Summary and Future Outlook 129
References 130
Artificial Photosynthesis Challenges: Water Oxidation at Nanostructured Interfaces 132
1 Introduction 133
1.1 Water Splitting 133
2 Oxygen Evolving Catalysts 135
2.1 Metal Oxides 136
2.2 Polyoxometalates 141
2.3 Light Driven Water Oxidation by POMs 143
3 Carbon Nanotubes Potential in Water Splitting Catalysis 147
3.1 Carbon Nanotubes as Active Components in Charge Separation Dyads 147
3.2 Carbon Nanotubes Applied to Water Splitting 152
4 Conclusions and Outlook 154
References 154
Photocatalytic Reduction of CO2: From Molecules to Semiconductors 162
1 Introduction 163
2 Photochemical CO2 Reduction by Metal Complexes 165
2.1 Single-Component Systems 165
2.1.1 Rhenium(I) Diimine Carbonyl Complexes 165
2.1.2 Metallo Porphyrins 169
2.1.3 p-Terphenyl 169
2.2 Multi-Component System 170
2.2.1 Ruthenium(II) Diimine Photosensitizers 170
2.2.2 Rhenium(I) Diimine Photosensitizer 173
2.2.3 Organic Photosensitizers 174
2.3 Supramolecular Photocatalysts 175
2.3.1 Ru(II)-Ni(I) 175
2.3.2 Ru(II)-Co(III) 177
2.3.3 Ru(II)-Re(I) 177
3 Photocatalytic Systems with Inorganic Semiconductor 178
3.1 Operating Principles 178
3.2 TiO2 and Related Materials 183
3.3 Other Semiconductors 187
3.4 Polyoxometalates 189
3.5 Hybrid Systems 189
4 Summary 191
References 192
Design of Heterogeneous Photocatalysts Based on Metal Oxides to Control the Selectivity of Chemical Reactions 196
1 Introduction 197
2 Titanium Dioxide 198
2.1 Oxidations 199
2.1.1 Alkanes 199
2.1.2 Aromatics 202
2.1.3 Alcohols 203
2.2 Reductions 205
2.3 Coupling Reactions 206
3 Highly Dispersed Oxides 209
3.1 Titanium 209
3.2 Chromium 212
3.3 Vanadium 213
4 Polyoxotungstates 214
4.1 Heterogenization by Impregnation 215
4.2 Heterogenization by Sol Gel Procedure 217
4.3 Heterogenization by Ionic Exchange 218
4.4 Heterogenization with Membranes 220
4.5 Heterogenization with Photoactive Semiconductors 221
5 Conclusions 222
References 223
Index 228