Hydrogen is the most abundant element in the universe. It has a place in the energy mix of the future, especially regarding fuel cells (FCs). This book is an investigation into FCs. Prominence is given to the subject of PEMFCs (proton exchange membrane fuel cells) as they offer interesting perspectives on transport and stationary applications. This being said, a number of technological and scientific obstacles remain to be overcome before an industrial level of development can be reached.
Table of Contents
Preface xi
1 Introduction 1
2 Introduction to Physics of the Solid State 8
2.1 Structure 8
2.1.1 Size Dependence of Properties 8
2.1.2 Crystal Structures 9
2.1.3 Face-Centered Cubic Nanoparticles 12
2.1.4 Tetrahedrally Bonded Semiconductor Structures 15
2.1.5 Lattice Vibrations 18
2.2 Energy Bands 20
2.2.1 Insulators, Semiconductors, and Conductors 20
2.2.2 Reciprocal Space 22
2.2.3 Energy Bonds and Gaps of Semiconductors 23
2.2.4 Effective Masses 28
2.2.5 Fermi Surfaces 29
2.3 Localized Particles 30
2.3.1 Donors, Acceptors, and Deep Traps 30
2.3.2 Mobility 31
2.3.3 Excitons 32
3 Methods of Measuring Properties 35
3.1 Introduction 35
3.2 Structure 36
3.2.1 Atomic Structures 36
3.2.2 Crystallography 37
3.2.3 Particle Size Determination 42
3.2.4 Surface Structure 45
3.3 Microscopy 46
3.3.1 Transmission Electron Microscopy 46
3.3.2 Field Ion Microscopy 51
3.3.3 Scanning Microscopy 51
3.4 Spectroscopy 58
3.4.1 Infrared and Raman Spectroscopy 58
3.4.2 Photoemission and X-Ray Spectroscopy 62
3.4.3 Magnetic Resonance 68
4 Properties of Individual Nanoparticles 72
4.1 Introduction 72
4.2 Metal Nanoclusters 74
4.2.1 Magic Numbers 74
4.2.2 Theoretical Modeling of Nanoparticles 75
4.2.3 Geometric Structure 78
4.2.4 Electronic Structure 81
4.2.5 Reactivity 83
4.2.6 Fluctuations 86
4.2.7 Magnetic Clusters 86
4.2.8 Bulk to Nanotransition 88
4.3 Semiconducting Nanoparticles 90
4.3.1 Optical Properties 90
4.3.2 Photofragmentation 92
4.3.3 Coulombic Explosion 93
4.4 Rare Gas and Molecular Clusters 94
4.4.1 Inert-Gas Clusters 94
4.4.2 Superfluid Clusters 95
4.4.3 Molecular Clusters 96
4.5 Methods of Synthesis 97
4.5.1 RF Plasma 97
4.5.2 Chemical Methods 98
4.5.3 Thermolysis 99
4.5.4 Pulsed Laser Methods 100
4.6 Conclusion 101
5 Carbon Nanostructures 103
5.1 Introduction 103
5.2 Carbon Molecules 103
5.2.1 Nature of the Carbon Bond 103
5.2.2 New Carbon Structures 105
5.3 Carbon Clusters 106
5.3.1 Small Carbon Clusters 106
5.3.2 Discovery of C60 107
5.3.3 Structure of C60 and Its Crystal 110
5.3.4 Alkali-Doped C60 110
5.3.5 Superconductivity in C60 112
5.3.6 Larger and Smaller Fullerenes 113
5.3.7 Other Buckyballs 113
5.4 Carbon Nanotubes 114
5.4.1 Fabrication 114
5.4.2 Structure 117
5.4.3 Electrical Properties 118
5.4.4 Vibrational Properties 122
5.4.5 Mechanical Properties 123
5.5 Applications of Carbon Nanotubes 125
5.5.1 Field Emission and Shielding 125
5.5.2 Computers 126
5.5.3 Fuel Cells 127
5.5.4 Chemical Sensors 128
5.5.5 Catalysis 129
5.5.6 Mechanical Reinforcement 130
6 Bulk Nanostructured Materials 133
6.1 Solid Disordered Nanostructures 133
6.1.1 Methods of Synthesis 133
6.1.2 Failure Mechanisms of Conventional Grain-Sized Materials 137
6.1.3 Mechanical Properties 139
6.1.4 Nanostructured Multilayers 141
6.1.5 Electrical Properties 142
6.1.6 Other Properties 147
6.1.7 Metal Nanocluster Composite Glasses 148
6.1.8 Porous Silicon 150
6.2 Nanostructured Crystals 153
6.2.1 Natural Nanocrystals 153
6.2.2 Computational Prediction of Cluster Lattices 153
6.2.3 Arrays of Nanoparticles in Zeolites 154
6.2.4 Crystals of Metal Nanoparticles 157
6.2.5 Nanoparticle Lattices in Colloidal Suspensions 158
6.2.6 Photonic Crystals 159
7 Nanostructured Ferromagnetism 165
7.1 Basics of Ferromagnetism 165
7.2 Effect of Bulk Nanostructuring of Magnetic Properties 170
7.3 Dynamics of Nanomagnets 172
7.4 Nanopore Containment of Magnetic Particles 176
7.5 Nanocarbon Ferromagnets 177
7.6 Giant and Colossal Magnetoresistance 181
7.7 Ferrofluids 186
8 Optical and Vibrational Spectroscopy 194
8.1 Introduction 194
8.2 Infrared Frequency Range 196
8.2.1 Spectroscopy of Semiconductors; Excitons 196
8.2.2 Infrared Surface Spectroscopy 198
8.2.3 Raman Spectroscopy 203
8.2.4 Brillouin Spectroscopy 210
8.3 Luminescence 213
8.3.1 Photoluminescence 213
8.3.2 Surface States 215
8.3.3 Thermoluminescence 221
8.4 Nanostructures in Zeolite Cages 222
9 Quantum Wells, Wires, and Dots 226
9.1 Introduction 226
9.2 Preparation of Quantum Nanostructures 227
9.3 Size and Dimensionality Effects 231
9.3.1 Size Effects 231
9.3.2 Conduction Electrons and Dimensionality 233
9.3.3 Fermi Gas and Density of States 234
9.3.4 Potential Wells 236
9.3.5 Partial Confinement 241
9.3.6 Properties Dependent on Density of States 242
9.4 Excitons 244
9.5 Single-Electron Tunneling 245
9.6 Applications 248
9.6.1 Infrared Detectors 248
9.6.2 Quantum Dot Lasers 251
9.7 Superconductivity 253
10 Self-Assembly and Catalysis 257
10.1 Self-Assembly 257
10.1.1 Process of Self-Assembly 257
10.1.2 Semiconductor Islands 258
10.1.3 Monolayers 260
10.2 Catalysis 264
10.2.1 Nature of Catalysis 264
10.2.2 Surface Area of Nanoparticles 264
10.2.3 Porous Materials 268
10.2.4 Pillared Clays 273
10.2.5 Colloids 277
11 Organic Compounds and Polymers 281
11.1 Introduction 281
11.2 Forming and Characterizing Polymers 283
11.2.1 Polymerization 283
11.2.2 Sizes of Polymers 284
11.3 Nanocrystals 285
11.3.1 Condensed Ring Types 285
11.3.2 Polydiacetylene Types 289
11.4 Polymers 292
11.4.1 Conductive Polymers 292
11.4.2 Block Copolymers 293
11.5 Supramolecular Structures 295
11.5.1 Transition-Metal-Mediated Types 295
11.5.2 Dendritic Molecules 296
11.5.3 Supramolecular Dendrimers 302
11.5.4 Micelles 305
12 Biological Materials 310
12.1 Introduction 310
12.2 Biological Building Blocks 311
12.2.1 Sizes of Building Blocks and Nanostructures 311
12.2.2 Polypeptide Nanowire and Protein Nanoparticle 314
12.3 Nucleic Acids 316
12.3.1 DNA Double Nanowire 316
12.3.2 Genetic Code and Protein Synthesis 322
12.4 Biological Nanostructures 324
12.4.1 Examples of Proteins 324
12.4.2 Micelles and Vesicles 326
12.4.3 Multilayer Films 329
13 Nanomachines and Nanodevices 332
13.1 Microelectromechanical Systems (MEMSs) 332
13.2 Nanoelectromechanical Systems (NEMSs) 335
13.2.1 Fabrication 335
13.2.2 Nanodevices and Nanomachines 339
13.3 Molecular and Supramolecular Switches 345
A Formulas for Dimensionality 357
A.1 Introduction 357
A.2 Delocalization 357
A.3 Partial Confinement 358
B Tabulations of Semiconducting Material Properties 361
Index 371
