Chemical Bonding at Surfaces and Interfaces (eBook)

Cover 1
Table of Contents 4
Preface 10
Chapter 1 Surface Structure 12
1. Why surface structure? 12
2. Methods of surface adsorbate structure determination 13
2.1. General comments 13
2.2. Electron scattering 14
2.3. X-ray scattering 17
2.4. Ion scattering 19
2.5. Spectroscopic methods and scanning probe microscopy 20
3. Adsorbate-induced surface reconstruction 22
4. Molecular adsorbates – local sites, orientations and intramolecular bondlengths 30
4.1. General issues and the case of CO on metals 30
4.2. Simple hydrocarbons on metals 32
4.3. Carboxylates on metals 37
4.4. Other substrates: molecules on Si 44
5. Chemisorption bondlengths 49
5.1. Metal surfaces 49
5.2. Oxide surfaces 55
6. Conclusions 59
Chapter 2 Adsorbate Electronic Structure and Bonding on Metal Surfaces 68
1. Introduction 68
2. Probing the electronic structure 69
3. Adsorbate electronic structure and chemical bonding 74
4. Adsorbate systems 79
5. Radical atomic adsorption 80
5.1. The electronic structure of N on Cu(100) 81
5.2. Chemical bonding of atomic adsorbates 86
6. Diatomic molecules 90
6.1. N2 adsorbed on Ni(100) 91
6.2. CO adsorbed on Ni(100) 102
6.3. CO adsorbed on Cu(100) and other metals 108
6.4. CO adsorbed in different sites 110
6.5. Coadsorption of CO and K on Ni(100) 112
7. Unsaturated hydrocarbons 114
7.1. Ethylene (C2H4) adsorbed on Ni(110) and Cu(110) 115
7.2. Benzene on Ni and Cu surfaces 122
7.3. Bond energetics and rehybridization from spin-uncoupling 124
8. Saturated hydrocarbons 130
8.1. n-Octane adsorbed on Cu(110) 131
8.2. Difference between octane on Ni and Cu surfaces 137
9. Lone pair interactions 138
9.1. Water adsorption on Pt and Cu surfaces 138
9.2. Adsorption of ammonia and the amino group in glycine on Cu(110) 142
10. Summary 145
Chapter 3 The Dynamics of Making and Breaking Bonds at Surfaces 154
1. Introduction 154
2. Theoretical background 157
2.1. Adiabatic dynamics (Born-Oppenheimer approximation) 157
2.2. Generic PES topologies 160
2.3. Dynamics vs. kinetics 163
2.3.1. Direct dissociation 164
2.3.2. Precursor-mediated dissociation 167
2.4. Detailed balance 168
2.5. Lattice coupling 169
2.5.1. Energy transfer in adsorption/scattering 170
2.5.2. Lattice coupling in direct molecular dissociation 174
2.6. Non-adiabatic dynamics 175
2.6.1. Hot electrons from chemistry 176
2.6.2. Chemistry from hot electrons 180
3. Experimental background 183
3.1. Experimental techniques 184
3.2. Typical measurements 186
3.2.1. Rate measurements 186
3.2.2. Adsorption-trapping and sticking 187
3.2.3. Desorption 190
3.2.4. Scattering 191
3.2.5. Initial state preparation 192
3.2.6. Photochemistry/femtochemistry 192
3.2.7. Single molecule chemistry (STM) 193
4. Processes 193
4.1. Atomic adsorption/desorption/scattering 194
4.1.1. Ar/Pt(111) 194
4.1.2. H/Cu(111) 197
4.2. Molecular adsorption/desorption/scattering 199
4.2.1. NO/Ag(111) 199
4.2.2. NO/Pt(111) 206
4.3. Direct dissociation/associative desorption 209
4.3.1. Activated dissociation 209
4.3.2. Weakly activated dissociation 225
4.3.3. Non-activated dissociation 227
4.4. Precursor-mediated dissociation/associative desorption 230
4.4.1. O2/Pt(111) 230
4.5. Direct and precursor-mediated dissociation 234
4.5.1. N2/W(100) 234
4.5.2. NH3/Ru(0001) 237
4.6. Langmuir-Hinschelwood chemistry 238
4.6.1. (O+CO)/Pt(111) 238
4.7. Eley-Rideal/Hot atom chemistry 241
4.7.1. H+H/Cu(111) 241
4.8. Hot electron chemistry 246
4.8.1. Photochemistry/femtochemistry 246
4.8.2. Single molecule chemistry 251
5. Summary and outlook 253
Chapter 4 Heterogeneous Catalysis 266
1. Introduction 266
2. Factors determining the reactivity of a transition metal surface 267
3. Trends in adsorption energies on transition metal surfaces 268
4. The d-band model 270
4.1. One-electron energies and bond energy trends 270
4.2. The Newns-Anderson model 273
5. Trends in chemisorption energies 278
5.1. Variations in adsorption energies from one metal to the next 278
5.2. Ligand effects in adsorption – changing the d band center 280
5.2.1. Variations due to changes in surface structure 281
5.2.2. Variations due to alloying 284
5.3. Ensemble effects in adsorption – the interpolation principle 286
6. Trends in activation energies for surface reactions 289
6.1. Electronic effects in surface reactivity 290
6.2. Geometrical effects in surface reactivity 292
7. Brønsted-Evans-Polanyi relationships in heterogeneous catalysis 294
7.1. Correlations from DFT calculations 294
7.2. Universal relationships 296
8. Activation barriers and rates 298
8.1. Transition state theory 299
8.2. Variational transition state theory and recrossings 302
8.3. Harmonic transition state theory (HTST) 303
9. Variations in catalytic rates – volcano relations 308
9.1. Dissociation rate-determined model 309
9.2. A Le Chatelier-like principle for heterogeneous catalysis 313
9.3. Including molecular precursor adsorption 314
9.4. Sabatier analysis 316
9.5. A realistic desorption model 318
9.6. Database of chemisorption energies 322
10. The optimization and design of catalyst through modeling 323
10.1. The low-temperature water gas shift (WGS) reaction 324
10.2. Methanation 324
11. Conclusions and outlook 327
Chapter 5 Semiconductor Surface Chemistry 334
1. Inroduction 334
2. Structure of semiconductor surfaces 336
2.1. Silicon surface structure 337
2.2. Germanium surface structure 341
3. Surface oxidation 342
3.1. Silicon 342
3.2. Germanium 344
4. Passivation of semiconductor surfaces 345
4.1. Silicon passivation 345
4.1.1. Hydride termination of silicon 345
4.2. Germanium passivation 346
4.2.1. Sulfide passivation of germanium 347
4.2.2. Chloride passivation of germanium 348
4.2.3. Hydride termination of germanium 348
5. Reactions at passivated semiconductor surfaces 350
5.1. Organic functionalization of semiconductor surface 350
5.2. Reaction with passivated silicon (Si-H and Si-Cl) 350
5.2.1. Hydrosilylation 350
5.2.2. Grignard reactions on silicon 356
5.3. Reaction with passivated germanium (Ge-H and Ge-Cl) 357
5.3.1. Grignard reactions on germanium 358
5.3.2. Hydrogermylation 359
5.3.3. Alkanethiol reactions on germanium 360
5.4. Reaction with compound semiconductors 361
6. Adsorption of organic molecules under vacuum conditions 362
6.1. Silicon surface chemistry 363
6.1.1. Cycloaddition reaction on Si(100)–2×1 363
6.1.2. Heterocycloadditions 372
6.1.3. Nucleophilic/electrophilic reactions 373
6.2. Germanium surface chemistry 380
6.2.1. Cycloaddition reactions on Ge(100)–2×1 381
6.2.2. Heterocycloadditions 383
6.2.3. Nucleophilic/electrophilic reactions 385
6.2.4. Multiple-layer reactions 387
6.3. Summary of concepts in organic functionalization 389
Chapter 6 Surface Electrochemistry 408
1. Introduction 408
2. Special features of electrochemical reactions 409
2.1. Electrochemical current and potential 410
2.2. Electrochemical interfaces 415
2.3. Models of electrochemical electron transfer kinetics 417
3. Electrochemistry at the molecular scale 423
3.1. Surface structure 423
3.2. Bonding of ions 424
3.3. Bonding of water 426
3.4. Experimental aspects of current/voltage properties 427
4. Electrocatalytic reaction processes 429
4.1. The electrocatalytic reduction of oxygen 431
4.1.1. Background 431
4.1.2. Mechanistic pathways 433
4.1.3. Electroreduction of oxygen on Pt and Pt alloys 434
4.1.4. Recent quantum chemical studies of the ORR mechanism 436
4.1.5. State-of-the-art ORR electrocatalyst concepts 442
4.2. The electrochemical oxidation of small organic molecules 446
4.2.1. The electrooxidation of carbon monoxide 449
4.2.2. The electrooxidation of formic acid and methanol 455
5. Summary and outlook 459
Chapter 7 Geochemistry of Mineral Surfaces and Factors Affecting Their Chemical Reactivity 468
1. Introduction 468
2. Environmental interfaces 472
2.1. Common minerals in Earth’s crust, soils, and atmosphere, weathering mechanisms and products, and less common minerals that contain or adsorb 472
2.2. Solubilities of Al- and Fe(III)-oxides and Al and Fe(III)-(oxy)hydroxides 477
2.3. Dissolution mechanisms at feldspar–water interfaces 480
2.4. The nature of metal oxide-aqueous solution interfaces – some basics 483
3. Factors affecting the chemical reactivity of mineral surfaces 489
3.1. The reaction of water vapor with metal oxide surfaces – surface science and theoretical studies of simplified model systems illustrating effects of 490
3.2. Grazing incidence EXAFS spectroscopic studies of Pb(II)aq adsorption on metal oxide surfaces – effect of differences in surface functional groups on 495
3.3. The structure of hydrated metal oxide surfaces from X-ray diffraction studies 499
3.4. X-ray standing wave studies of the electrical double layer at solid-aqueous solution interfaces and in situ measurements of surface reactivity 507
3.5. Effect of organic coatings and microbial biofilms on metal oxide surface reactivity – X-ray standing wave studies of metal ion partitioning between 510
4. Conclusions 515
Index 522