From Molecules to Materials (eBook)

Dr. Elena A. Rozhkova, Ph.D. is a Scientist and a Principal Investigator at the Center for Nanoscale Materials (CNM), Argonne National Laboratory (ANL), USA. Rozhkova’s major research interests include nanoscience and nanotechnology for clean energy, bio-inspired catalysis, complex energy gradients in biology and at the nano-bio interface, nanomaterials-enabled signaling within biological machinery, advanced synchrotron X-ray imaging. At the Center for Nanoscale Materials, US DOE premier facility for nanomaterials and nanotechnology, Dr. Rozhkova is a key scientific contact for diversified users’ community dealing with application of biological principles in design and development of functional nanomaterialsfor emerging energy and biomedical technologies.Katsuhiko Ariga is the Director of Supermolecules Unit and Principal Investigator of World Premier International (WPI) Research Center for Materials Nanoarchitectonics (MANA) at the National Institute for Materials Science (NIMS) as well as Fellows of Royal Society of Chemistry, Highly Cited Researcher (2014, Thompson Reuters, Materials Science), and a member of the Global Agenda Councils on Nanotechnology for World Economic Forum. His research field is based on supermolecular chemistry and surface science, including the boundary research areas of organic chemistry, physical chemistry, biochemistry, and materials chemistry. His major interests are the fabrication of novel functional nanostructures based on molecular recognition and self-assembly including Langmuir-Blodgett films, layer-by-layer films, and mesoporous materials.

Preface 6
Contents 8
Semiconductors for Photocatalytic and Photoelectrochemical Solar Water Splitting 10
1 Introduction 10
2 Thermodynamics of Photocatalytic and Photoelectrochemical Water Splitting 11
2.1 Photocatalytic Water Splitting on a Semiconductor Particle 12
2.2 PEC Water Splitting on a Thin-Film Semiconductor Photoelectrode 14
3 Materials Design of Visible-Light-Driven Photocatalysts 16
3.1 Doping 17
3.2 Solid Solution Photocatalysts 19
3.3 Elemental Substitution of O by S and N 20
4 Measurement of Water-Splitting Activity 22
4.1 Apparatus 22
4.2 Efficiency 24
4.3 Test Reaction with Sacrificial Reagents 27
5 Recent Advancements in Photocatalytic Water Splitting 28
5.1 Overall Water Splitting with a Single Photocatalyst 28
5.1.1 Oxide Photocatalysts Active Under UV Light Illumination 28
5.1.2 (Oxy)nitride Photocatalysts for Visible-Light-Driven Water Splitting 30
5.1.3 Coloading of Hydrogen and Oxygen Evolution Cocatalysts 32
5.2 Z-Scheme Water Splitting 35
6 Advancements in Photoelectrochemical Water Splitting 39
6.1 Photoelectrode Preparation Methods 39
6.2 Earth-Abundant Photoelectrode Materials 42
6.2.1 BiVO4 43
6.2.2 Hematite (?-Fe2O3) 43
6.2.3 WO3 45
6.2.4 Cu2O 46
7 Mechanistic Aspects of the Water-Splitting Reaction 47
7.1 Introduction 47
7.2 Kinetic Aspects of Photocatalytic Water Splitting 48
7.2.1 Light Intensity and Cocatalyst Loading 48
7.2.2 Hydrogen–Deuterium Isotope Effect 50
7.2.3 Activation Energy 52
7.3 Charge Separation Efficiency and Change Injection Efficiency in Photoelectrochemical Water Splitting 53
7.4 Summary 56
8 Summary 56
References 58
Artificial Photosynthesis Producing Solar Fuels: Natural Tactics of Photosynthesis 66
1 Introduction 67
2 From Natural Photosynthesis to Artificial Photosynthesis 68
3 Four Elements to Implement Artificial Photosynthesis 69
3.1 Light-Harvesting Antenna 69
3.2 Reaction Center 71
3.3 Oxidation Catalyst 73
3.4 Reduction Catalyst 75
Conclusion 76
References 77
Artificial Photosynthesis: From Molecular to Hybrid Nanoconstructs 79
1 Introduction 79
1.1 Natural Photosynthesis as Inspiration for Artificial Photosynthesis 81
2 Evolution of Molecular Reaction Centers 82
2.1 Early Molecular Reaction Centers 82
2.2 PCET in Organic Systems 84
3 Organic Dye: Metal Oxide Hybrid Systems 86
3.1 Design and Application of Dye–Semiconductor Hybrid Systems 86
3.2 Anchoring Groups and Bridges 89
3.3 Dye–Semiconductor Nanoparticle (Dye–SNP) Systems 91
3.4 Relevance of TiO2 Trap States in PEC Dynamics 94
3.5 PCET in Complexes Models of Dye–Semiconductor Nanoparticles Systems 96
3.6 PCEs for Water Splitting 98
Conclusions 100
References 101
Enzymes as Exploratory Catalysts in Artificial Photosynthesis 107
1 Introduction 107
2 A Picture of the Concepts 108
3 Enzymes and Their Proficiency 109
3.1 The Importance of the Environment Beyond the Catalyst Centre 109
3.2 Hydrogenases 112
3.3 Carbon Dioxide-Reducing Enzymes 113
3.4 The Oxygen-Evolving Enzyme 114
4 Practicalities, Methodology: Linking Enzymes to Semiconductors 116
4.1 General Properties of Important Semiconducting Materials 116
4.2 Photoelectrochemical vs. Photochemical Water Splitting 117
4.2.1 Photoelectrochemical Cells 117
4.2.2 Photochemical Systems 119
4.3 Linking Enzymes to Semiconductors 121
5 Progress on Steady-State Rates and Stability 122
6 Advanced Mechanistic Studies of Enzyme-Catalysed AP 123
6.1 Rate and Efficiency Parameters 123
6.2 Case Studies 124
6.2.1 Continuous Catalytic Rates 124
6.2.2 Transient Processes 125
7 Where Do We Go from Here? 127
References 128
Solar Photoelectrochemical Water Splitting with Bioconjugate and Bio-Hybrid Electrodes 132
1 Introduction 132
2 The Inorganic Electrode Backbone Materials 133
3 Development of Biohybrid Electrodes for Photoelectrochemical Water Splitting 133
3.1 Biohybrid Photoanodes 133
3.2 Biohybrid Photocathodes 138
3.3 Hybrid Photocatalysts for Photoelectrochemical Water Splitting 140
3.4 Hydrogenases as Molecular Hydrogen-Evolving Complexes for Making Biohybrid Photocathodes 140
4 Oxygen-Evolving Complexes from Photosynthesis and the Respective Biohybrid Electrodes for Photoelectrochemical Water Splitting 142
5 Light Antenna Complex from Photosynthesis and Its Biohybrid Electrode 144
6 Synthesis and Analytical Methods for Bioconjugated and Biohybrid Electrode 147
7 Conclusion and Outlook 150
References 152
Hybrid (Enzymatic and Photocatalytic) Systems for CO2-Water Coprocessing to Afford Energy-Rich Molecules 155
1 Introduction 156
2 Enzymatic Reduction of Carbon Dioxide 156
2.1 Enzymes Catalyzing the CO2 Conversion 157
2.1.1 Carboxylation Enzymes 158
2.1.2 CO2-Reducing Enzymes 158
2.2 Man-Made Systems for the Back Conversion of Oxidized Forms of Cofactors 160
3 Photocatalytic Systems Cooperating with Enzymes 161
3.1 Photocatalytic Regeneration of the Cofactor NAD+ 162
3.1.1 UV Light-Induced Processes 163
3.1.2 Visible Light-Induced Processes 163
3.2 Reduction of Carbon Dioxide in Multicomponent Photocatalytic/Enzymatic Systems 167
4 Photoelectrocatalytic Systems for NAD+ Reduction to NADH 169
5 Other Systems 171
6 Conclusions and Outlook 172
References 173
Current Challenges of CO2 Photocatalytic Reduction Over Semiconductors Using Sunlight 176
1 Routes for the Activation of the CO2 Molecule 177
2 Fundamentals of Semiconductor Photocatalysis 178
3 Artificial Photosynthesis for CO2 Reduction 180
4 Additional Challenges of CO2 Photoreduction Over Semiconductors 188
4.1 Analysis of the Products 188
4.2 Dealing with Impurities 189
4.3 Stability of the Photocatalysts 190
4.4 Designing Efficient Solar Photoreactors 191
5 Concluding Remarks 193
References 193
Functionalized Nanocarbons for Artificial Photosynthesis: From Fullerene to SWCNT, Carbon Nanohorn, and Graphene 197
1 Introduction 198
2 Photoinduced Electron Transfer of Fullerene-Donor Systems 201
2.1 Molecular Orbital Description of Photoinduced Electron Transfer 201
2.2 Donor and Acceptor Mixture in Polar Solvents 203
2.3 Charge Separation via Acceptor Excitation in Covalently Connected C60–Phenothiazine System 205
2.4 Charge Separation via Donor Excitation for Substituted Porphyrin Connected to C60 Molecule 208
2.5 Cascade Electron and Hole Transfer After Photoinduced Charge Separation 211
2.6 Fullerene–Porphyrin Molecule with Flexible Connector 212
2.7 Fullerene–Zn Porphyrin Coordination Systems 213
2.8 Successive Energy Transfer and Electron Transfer 215
2.9 Photoinduced Charge Separation Through Long Spacers 217
2.10 Output Systems of Electron and Hole from the Charge-­Separated States 219
2.11 Application to Solar Cell 220
3 Photosensitizer–SWCNT Systems 221
3.1 Visible-Light Photosensitizing Molecule on SWCNT 221
3.2 Covalently Linked Porphyrin–SWCNT 223
3.3 Supramolecular Porphyrin–(Pyrene)/SWCNT Hybrid 225
3.4 Supramolecular Fullerene–(Pyrene)/SWCNT Hybrid 229
3.5 Supramolecular Fullerene–Porphyrin–SWCNT “Triple” Hybrid 231
3.6 Supramolecular Porphyrin–ssDNA–SWCNT Triple Hybrids 233
4 Photosensitizer–Carbon Nanohorn Systems 235
5 Photosensitizer–Graphene Systems 237
6 Summary and Perspective 241
References 242
Plasmonic Photocatalysts with Wide Light Absorption Spectra and High Charge Separation Efficiencies 245
1 Introduction 245
2 Basic Principles of LSPRs 246
3 Proposed Mechanisms on Charge Transfer 247
3.1 Direct Electron Transfer (DET) from Metal to Semiconductor 247
3.2 Local Electromagnetic Field (LEMF) Enhancement 247
3.3 Resonant Energy Transfer (RET) 248
4 Plasmonic Photocatalysts 248
4.1 Noble Metal–Semiconductor Composites 248
4.2 Silver Halide Plasmonic Photocatalysts 254
4.3 Nonmetallic Plasmonic Nanomaterials 259
4.3.1 Extrinsic Doping of Semiconductors or Metal Oxides 259
4.3.2 Self-Doped Nonstoichiometric Semiconductors or Metal Oxides 261
5 Conclusions 265
References 266
Soft X-Ray Spectroscopy and Electronic Structure of 3d Transition Metal Compounds in Artificial Photosynthesis Materials 272
1 Introduction 272
1.1 Principles of Photocatalysis 274
1.2 Functional Catalyst Materials 275
2 Representative Catalyst Materials and the Tailoring of Their Electronic and Optical Properties 277
2.1 Alteration of Structural and Morphological Properties 277
2.2 Alteration of the Electronic Properties by Introduction of Transition Metal Impurity Elements 278
3 Synchrotron-Based X-Ray Spectroscopy 281
3.1 Principles 281
3.2 X-Ray Absorption and Emission Spectroscopy 282
3.3 In Situ Experiments 284
4 Soft X-Ray Spectroscopy Studies on Nanostructured Metal Oxide Complexes 284
4.1 Correlation Between Particle Size and Electronic Structure in TiO2 and Co Complexes 285
4.2 Orbital Anisotropy and Polarization-Dependent XAS 286
4.3 Evolution in the Electronic Structure of TiO2 and ZnO upon Introduction of Transition Metal Impurity Elements 288
4.4 Reduction in the Band Gap of TiO2 by Hydrogenation of the Oxide Surface 293
References 294
Assessment of the Electronic Structure of Photo-electrodes with X-Ray and Electron Spectroscopy 300
1 Introduction 300
2 Ex Situ Studies of the Electrode Bulk 302
3 Ex Situ Studies of the Electrode Surface 307
4 In Situ Investigation of the Semiconductor Subsurface and Depletion Layer 313
References 322