PEM fuel cell electrocatalysts and catalyst layers : fundamentals and applications

Proton exchange membrane (PEM) fuel cells are promising clean energy converting devices with high efficiency and low to zero emissions. Such power sources can be used in transportation, stationary, portable and micro power applications. The key components of these fuel cells are catalysts and catalyst layers. "PEM Fuel Cell Electrocatalysts and Catalyst Layers" provides a comprehensive, in-depth survey of the field, presented by internationally renowned fuel cell scientists. The opening chapters introduce the fundamentals of electrochemical theory and fuel cell catalysis. Later chapters investigate the synthesis, characterization, and activity validation of PEM fuel cell catalysts. Further chapters describe in detail the integration of the electrocatalyst/catalyst layers into the fuel cell, and their performance validation. Researchers and engineers in the fuel cell industry will find this book a valuable resource, as will students of electrochemical engineering and catalyst synthesis.

Author Notes

Dr Jiujun Zhang is a Senior Research Officer and PEM Catalysis Core Competency Leader at the National Research Council of Canada Institute for Fuel Cell Innovation (NRC-IFCI). Dr Zhang has over twenty-six years of R&D experience in theoretical and applied electrochemistry, including over twelve years of fuel cell R&D (among these six years at Ballard Power Systems and four years at NRC-IFCI), and three years of electrochemical sensor experience. Dr Zhang holds seven adjunct professorships, including one at the University of Waterloo and one at the University of British Columbia. His research is based on: low/non-Pt cathode catalyst development with long-term stability for catalyst cost reduction; preparation of novel material-supported Pt catalysts through ultrasonic spray pyrolysis; catalyst layer/cathode structure; fundamental understanding through first principles theoretical modeling; catalyst layer characterization and electrochemical evaluation; and preparation of cost-effective MEAs for fuel cell testing and evaluation. Dr Zhang has co-authored more than 140 research papers published in refereed journals and holds over ten US patents. He has also produced in excess of seventy industrial technical reports. Dr Zhang is an active member of The Electrochemical Society, the International Society of Electrochemistry, and the American Chemical Society.

Xiao-Zi Yuan and Haijiang WangChaojie Song and Jiujun ZhangHui Li and Kunchan Lee and Jiujun ZhangElod GyengeZheng ShiHui Li and Chaojie Song and Jianlu Zhang and Jiujun ZhangPei Kang ShenMichael H. Eikerling and Kourosh Malek and Qianpu WangChristina Bock and Helga Halvorsen and Barry MacDougallShijun Liao and Baitao Li and Yingwei LiZhigang QiHansan Liu and Jiujun ZhangHansan Liu and Dingguo Xia and Jiujun ZhangXueliang Sun and Madhu Sudan SahaKunchan Lee and Lei Zhang and Jiujun ZhangSiyu YeSiyu YeChaojie Song and Rob Hui and Jiujun ZhangHuamin Zhang and Xiaoli Wang and Jianlu Zhang and Jiujun ZhangRadenka MaricJianlu Zhang and Jiujun ZhangWei XingJing Li

1 PEM Fuel Cell Fundamentals	p. 1
1.1 Overview	p. 1
1.1.1 Introduction	p. 1
1.1.2 Main Cell Components and Materials	p. 11
1.1.3 PEM Fuel Cell Operation	p. 17
1.1.4 PEM Fuel Cell Applications	p. 25
1.2 Thermodynamics	p. 31
1.2.1 Basic Reactions	p. 31
1.2.2 Heat of Reaction	p. 41
1.2.3 Effect of Operation Conditions on Reversible Fuel Cell Potential	p. 42
1.2.4 Open Circuit Voltage	p. 44
1.2.5 Fuel Cell Efficiency	p. 48
1.2.6 Summary	p. 50
1.3 Reaction Kinetics	p. 53
1.3.1 Electrode Reactions	p. 53
1.3.2 Reaction Rate	p. 53
1.3.3 Mass Transfer	p. 60
1.3.4 Multiple Kinetics	p. 65
1.3.5 Polarization Curve and Voltage Losses	p. 67
1.3.6 Measures to Improve Cell Performance	p. 78
References	p. 79
2 Electrocatalytic Oxygen Reduction Reaction	p. 89
2.1 Introduction	p. 89
2.1.1 Electrochemical O 2 Reduction Reactions	p. 89
2.1.2 Kinetics of the O 2 Reduction Reaction	p. 90
2.1.3 Techniques Used in Electrocatalytic O 2 Reduction Reactions	p. 93
2.2 Oxygen Reduction on Graphite and Carbon	p. 101
2.2.1 Oxygen Reduction Reaction Mechanisms	p. 102
2.2.2 Kinetics of the ORR on Carbon Materials	p. 107
2.2.3 Catalytic Sites on Carbon Materials	p. 108
2.3 Oxygen Reduction Catalyzed by Quinone and Derivatives	p. 109
2.3.1 AO Process for O 2 Reduction to Produce H 2 O 2	p. 109
2.3.2 ORR Mechanism Electrochemically Catalyzed by Quinone	p. 110
2.4 Oxygen Reduction on Metal Catalysts	p. 110
2.4.1 ORR Mechanism on Pt	p. 110
2.4.2 Mixed Pt Surface and Rest Potential on Pt	p. 112
2.4.3 ORR Kinetics on Pt	p. 113
2.4.4 ORR on Pt Alloys	p. 114
2.4.5 Catalytic ORR on Other Metals	p. 116
2.5 ORR on Macrocyclic Transition Metal Complexes	p. 117
2.5.1 ORR Mechanisms Catalyzed by Transition Metal Macrocyclic Complexes	p. 117
2.5.2 Transition Metal Macrocycles as ORR Catalysts	p. 117
2.5.3 ORR Kinetics Catalyzed by Transition Metal Macrocyclic Complexes	p. 121
2.6 ORR Catalyzed by Other Catalysts	p. 122
2.6.1 ORR Catalyzed by Transition Metal Chalcogenides	p. 122
2.6.2 ORR Catalyzed by Transition Metal Carbide	p. 124
2.7 Superoxide Ion	p. 125
2.7.1 Production of Superoxide Ion by Other Methods	p. 125
2.7.2 Properties of Superoxide Ion	p. 126
2.7.3 Stability of Superoxide Ion	p. 127
2.7.4 Superoxide Production by Electrocatalysis	p. 127
2.8 Conclusions	p. 129
References	p. 129
3 Electrocatalytic H 2 Oxidation Reaction	p. 135
3.1 Introduction	p. 135
3.2 Electrooxidation of Hydrogen	p. 136
3.2.1 Mechanism of the Hydrogen Oxidation Reaction	p. 136
3.2.2 Thermodynamic Considerations for the Hydrogen Electrode Reaction	p. 138
3.2.3 Kinetics of the Hydrogen Oxidation Reaction	p. 138
3.2.4 Hydrogen Adsorption Behavior	p. 143
3.2.5 Kinetic Parameters of the Hydrogen Oxidation Reaction	p. 147
3.3 Electrocatalysis of Hydrogen Oxidation	p. 149
3.3.1 Platinum and Platinum Group Metals (Pt, Ru, Pd, Ir, Os, and Rh)	p. 149
3.3.2 Carbides	p. 156
3.3.3 Raney Nickel	p. 156
3.3.4 Typical Example Analysis - PtRu Alloy as a CO-tolerant Catalyst for the HOR	p. 157
3.4 Conclusions	p. 159
References	p. 159
4 Electrocatalytic Oxidation of Methanol, Ethanol and Formic Acid	p. 165
4.1 Introduction	p. 165
4.1.1 Historical Overview: 1960-1990	p. 165
4.1.2 Objectives	p. 171
4.2 Reaction Pathways, Catalyst Selection and Performance: Example Analysis	p. 172
4.2.1 Methanol Electrooxidation	p. 172
4.2.2 Formic Acid Electrooxidation	p. 201
4.2.3 Ethanol Electrooxidation	p. 219
4.2.4 Non-precious Metal Catalysts for Methanol, Formic Acid, and Ethanol Oxidation	p. 224
4.3 Advances in Anode Catalyst Layer Engineering: Example Analysis	p. 230
4.3.1 Engineering of the Catalyst Surface and Morphology	p. 230
4.3.2 The Catalytic Interface: Catalyst/Support/Ionomer Interaction	p. 236
4.4 Conclusions	p. 269
References	p. 270
5 Application of First Principles Methods in the Study of Fuel Cell Air-Cathode Electrocatalysis	p. 289
5.1 Introduction	p. 289
5.2 Background	p. 290
5.2.1 Theoretical Methods	p. 290
5.2.2 Oxygen Reduction Reaction	p. 291
5.3 Surface Adsorption	p. 293
5.3.1 Computational Methods	p. 294
5.3.2 Adsorption on Transition Metals	p. 295
5.3.3 Adsorption on Bimetallic Alloys	p. 299
5.4 Activation Energy	p. 306
5.4.1 Computational Method	p. 306
5.4.2 Example Calculations	p. 307
5.5 Thermodynamic Properties: Reversible Potential and Reaction Energy	p. 311
5.5.1 Reversible Potential	p. 311
5.5.2 Reaction Thermodynamics	p. 313
5.6 Study of Non-noble Catalysts	p. 316
5.7 Summary	p. 324
References	p. 324
6 Catalyst Contamination in PEM Fuel Cells	p. 331
6.1 Introduction	p. 331
6.2 Anode Catalyst Layer Contamination	p. 331
6.2.1 Impacts of Carbon Dioxide	p. 332
6.2.2 Impacts of Hydrogen Sulfide (H 2 S)	p. 334
6.2.3 Impacts of Ammonium (NH 3 )	p. 337
6.2.4 Modeling of the Contamination of the PEMFC Anode Catalyst	p. 337
6.2.5 Mitigation of Anode Contamination	p. 339
6.3 Cathode Catalyst Layer Contamination	p. 339
6.3.1 SO x Contamination	p. 340
6.3.2 NO x Contamination	p. 343
6.3.3 NH 3 and H 2 S Contamination	p. 346
6.3.4 Volatile Organic Compounds (VOCs) Contamination	p. 347
6.3.5 Ozone Contamination	p. 348
6.3.6 The Contamination Effects of Multi-contaminants	p. 348
6.3.7 Modeling of PEMFC Cathode Catalyst Contamination	p. 349
6.4 Additive Effects of Anode and Cathode Contamination	p. 349
6.5 Summary	p. 350
References	p. 351
7 PEM Fuel Cell Catalyst Layers and MEAs	p. 355
7.1 Fundamentals of Catalyst Layers	p. 355
7.1.1 Components and Structure	p. 356
7.1.2 Functions and Reactions	p. 356
7.1.3 Factors Affecting the Performance of CLs	p. 359
7.1.4 Catalyst Layers for Liquid Fuel Cells	p. 366
7.1.5 Catalyst Layers for Anion Exchange Membrane Fuel Cells	p. 367
7.2 Principles of Membrane Electrode Assembly (MEA)	p. 369
7.2.1 Classification of MEA Materials	p. 370
7.2.2 Methods for MEA Fabrication	p. 371
7.2.3 Technical Consideration	p. 372
7.2.4 MEA for Anion Exchange Membrane Fuel Cells	p. 373
7.3 Conclusions	p. 374
References	p. 374
8 Catalyst Layer Modeling: Structure, Properties and Performance	p. 381
8.1 Introduction	p. 381
8.2 Understanding Structure and Operation of Catalyst Layers	p. 383
8.2.1 Challenges for the Structural Design	p. 383
8.2.2 Porous Electrode Theory: Historical Perspective	p. 384
8.2.3 Misapprehensions and Controversial Issues	p. 387
8.2.4 Effectiveness of Catalyst Utilization	p. 388
8.2.5 Evaluating the Performance of CLs	p. 391
8.3 State of the Art in Theory and Modeling: Multiple Scales	p. 395
8.4 Structural Formation of Catalyst Layers and Effective Properties	p. 398
8.4.1 Molecular Dynamics Simulations	p. 398
8.4.2 Atomistic MD Simulations of CLs	p. 400
8.4.3 Meso-scale Model of CL Microstructure Formation	p. 403
8.4.4 Structure-related Effective Properties of CLs	p. 407
8.5 Performance Modeling and Optimization Studies	p. 412
8.5.1 General Framework of Performance Modeling	p. 412
8.5.2 Transport and Reaction in Catalyst Layers	p. 415
8.5.3 Spherical Agglomerates	p. 418
8.5.4 Main Results of the Macrohomogeneous Approach	p. 425
8.5.5 Water Management in CCLs	p. 428
8.6 Comparison and Evaluation of Catalyst Layer Designs	p. 433
8.6.1 Conventional Catalyst Layers	p. 434
8.6.2 Ultra-thin Two-phase Catalyst Layers	p. 434
8.7 Summary and Outlook	p. 438
References	p. 439
9 Catalyst Synthesis Techniques	p. 447
9.1 Introduction	p. 447
9.2 Catalysis Synthesis Methods	p. 447
9.2.1 Low-temperature Chemical Precipitation	p. 448
9.2.2 Colloidal	p. 448
9.2.3 Sol-gel	p. 449
9.2.4 Impregnation	p. 450
9.2.5 Microemulsions	p. 451
9.2.6 Electrochemical	p. 453
9.2.7 Spray Pyrolysis	p. 454
9.2.8 Vapor Deposition	p. 455
9.2.9 High-energy Ball Milling	p. 457
9.3 Particle Size and Shape Control	p. 458
9.3.1 Mechanism for Size Control Using Colloidal Synthesis Methods	p. 460
9.3.2 Size Control Using Electrochemical Methods	p. 463
9.3.3 Assistance of Templates and Template Preparation	p. 463
9.3.4 Shape Control	p. 467
9.4 Bi-metallic Catalysts	p. 468
9.4.1 Synthesis of Alloy versus Two-phase Catalysts	p. 468
9.4.2 Sub-monolayer Deposition of Ad-metals	p. 472
9.5 Non-noble Metal Catalyst Synthesis	p. 474
9.5.1 Macrocyclic Complexes	p. 474
9.5.2 Methanol Tolerance and the Economics of these Catalysts	p. 476
9.5.3 Transition Metal Chalcogenides	p. 477
9.5.4 Conclusions	p. 478
References	p. 479
10 Physical Characterization of Electrocatalysts	p. 487
10.1 Introduction	p. 487
10.2 Analysis of Composition and Phase of Catalyst	p. 488
10.2.1 X-ray Diffraction (XRD) and Electron Diffraction (ED)	p. 488
10.2.2 X-ray Fluorescence (XRF), X-ray Emission (XRE), and Proton-induced X-ray Emission (PIXE)	p. 497
10.3 Measurement of Physical Surface Area and Electrochemical Active Surface Area	p. 498
10.3.1 BET Method and Physical Surface Area	p. 498
10.3.2 Electrochemical Hydrogen Adsorption/Desorption	p. 499
10.3.3 Typical Examples Analysis	p. 501
10.4 Morphology of Catalysts and Their Active Components	p. 505
10.4.1 Scanning Electron Microscopy (SEM)	p. 505
10.4.2 Transmission Electron Microscopy	p. 506
10.4.3 Typical Examples	p. 507
10.5 The Structure and Crystallography of Surface and Small Active Component Particles	p. 512
10.5.1 Principles of Electron Spectroscopy for Chemical Analysis (ESCA)	p. 512
10.5.2 X-ray Photoelectron Spectroscopy (XPS)	p. 513
10.5.3 UV-induced Photoelectron Spectroscopy (UVPS)	p. 519
10.5.4 Energy Dispersive Spectroscopy (EDS) and its Application	p. 522
10.6 Analysis of the Stability of Catalysts by the Thermal Analysis Method	p. 525
10.6.1 Principles	p. 525
10.6.2 Application	p. 526
10.6.3 Typical Examples of Analysis	p. 527
10.7 Other Structural Techniques for Characterizing the Bulk and Surface of Electrocatalysts	p. 532
10.7.1 FTIR and UV-VIS	p. 532
10.7.2 TPD/TPR	p. 534
10.8 Conclusion	p. 536
References	p. 536
11 Electrochemical Methods for Catalyst Activity Evaluation	p. 547
11.1 Electrochemical Cells	p. 547
11.1.1 Introduction	p. 547
11.1.2 Conventional 3-Electrode Cells	p. 548
11.1.3 Half-cells	p. 551
11.1.4 Single Cells	p. 553
11.2 Brief Principles of Electrochemical Instrumentation	p. 556
11.3 Cyclic Voltammetry	p. 556
11.3.1 Basic Principles	p. 556
11.3.2 Potential Step Experiment	p. 558
11.3.3 Instrumentation: Potentiostat	p. 559
11.3.4 Applications	p. 560
11.4 Rotating Disk and Rotating Ring-disk Electrode Techniques	p. 567
11.4.1 Theories and Principles	p. 567
11.4.2 Instrumentation	p. 570
11.4.3 Fuel Cell-related Applications	p. 570
11.5 Electrochemical Impedance Spectroscopy	p. 573
11.5.1 Theories and Principles	p. 573
11.5.2 Instrumentation	p. 578
11.5.3 Application in Fuel Cells	p. 578
11.6 Current Interruption and Current Pulse Techniques	p. 585
11.6.1 Principles and Instrumentation	p. 585
11.6.2 Application in Fuel Cells	p. 587
11.7 Steady-state I-V Polarization	p. 588
11.7.1 Principles and Instrumentation	p. 588
11.7.2 Fuel Cell Hardware	p. 589
11.7.3 Fuel Cell Performance	p. 590
11.8 Durability Evaluation	p. 592
11.8.1 Introduction	p. 592
11.8.2 Techniques	p. 593
11.9 Summary	p. 602
List of Symbols	p. 602
References	p. 604
12 Combinatorial Methods for PEM Fuel Cell Electrocatalysts	p. 609
12.1 Introduction	p. 609
12.1.1 Combinatory Material Chemistry	p. 609
12.1.2 Electrocatalysis in PEM Fuel Cells	p. 611
12.2 Combinatorial Methods for Fuel Cell Electrocatalysis	p. 612
12.2.1 Catalyst Library Preparation	p. 612
12.2.2 Catalyst Activity Down-selection	p. 617
12.3 Combinatorial Discoveries of Fuel Cell Electrocatalysts	p. 622
12.3.1 Low/Non-platinum Content Catalysts for PEM Fuel Cell Cathodes	p. 623
12.3.2 CO-tolerant Catalysts for PEM Fuel Cell Anodes	p. 625
12.3.3 Platinum Alloy Catalysts for Direct Methanol Fuel Cell Anodes	p. 625
12.3.4 Methanol-tolerant Catalysts for Direct Methanol Fuel Cell Cathodes	p. 627
12.4 Conclusions	p. 628
References	p. 629
13 Platinum-based Alloy Catalysts for PEM Fuel Cells	p. 631
13.1 Introduction	p. 631
13.2 Pt-based Alloy Catalysts for PEM Fuel Cell Cathodes	p. 632
13.2.1 The Alloying Effect on Cathode Catalyst Activity	p. 632
13.2.2 Mechanism of the Alloying Effect on Cathode Catalysts	p. 635
13.2.3 Stability of Pt-based Alloy Cathode Catalysts	p. 640
13.3 Pt-based Alloy Catalysts for DMFC Anodes	p. 643
13.3.1 The Alloying Effect on Anode Catalyst Activity	p. 643
13.3.2 Mechanism of the Alloying Effect on Anode Catalysts	p. 646
13.3.3 The Stability of Pt-based Alloy Anode Catalysts	p. 649
13.4 Concluding Remarks	p. 650
References	p. 651
14 Nanotubes, Nanofibers and Nanowires as Supports for Catalysts	p. 655
14.1 Introduction	p. 655
14.1.1 The Importance of Combining Nanotechnology and Clean Energy	p. 655
14.1.2 One-dimensional Nanomaterials Based New Catalyst Supports	p. 656
14.2 Synthesis and Characterization of Carbon Nanotubes, Nanofibers, and Nanowires	p. 657
14.2.1 Structure and Synthesis Methods for Carbon Nanotubes	p. 657
14.2.2 Structure and Synthesis Methods for Carbon Nanofibers	p. 661
14.2.3 Structure and Synthesis Methods for Nanowires	p. 661
14.3 Synthesis and Characterization of Pt Catalysts Supported on Carbon Nanotubes, Carbon Nanofibers and Metal Oxide Nanowires	p. 665
14.3.1 Introduction	p. 665
14.3.2 Methods for Depositing Pt Catalysts on Carbon Nanotubes (Pt/CNTs)	p. 666
14.3.3 Methods for Depositing Pt Catalysts on Carbon Nanofibers (Pt/CNFs)	p. 682
14.3.4 Methods for Depositing Pt Catalysts on Metal Oxide Nanowires (Pt/NWs)	p. 684
14.3.5 Methods of Functionalizing of Carbon Nanotubes and Nanofibers-based Fuel Cell Electrodes	p. 687
14.4 Activity Validation of the Synthesized Catalysts in a Fuel Cell Operation	p. 693
14.4.1 Fabrication of Membrane Electrode Assembly for Carbon Nanotubes and Nanofibers-based Catalysts	p. 693
14.4.2 Performance of Carbon Nanotubes and Nanofibers Membrane Electrode Assembly	p. 697
14.5 Stability of Carbon Nanotubes and Nanofibers-based Fuel Cell Electrodes	p. 700
14.6 Conclusions and Future Perspective	p. 702
References	p. 704
15 Non-noble Electrocatalysts for the PEM Fuel Cell Oxygen Reduction Reaction	p. 715
15.1 Introduction	p. 715
15.2 Transition Metal Macrocycles for the Oxygen Reduction Reaction	p. 716
15.2.1 The Central Transition Metal Effect	p. 717
15.2.2 The Ligand Effect	p. 719
15.2.3 The Heat-treatment Effect	p. 720
15.2.4 The Effect of the Synthesis Method	p. 721
15.3 Non-noble Transition Metal Carbides and Nitrides for the ORR	p. 725
15.3.1 Carbides	p. 725
15.3.2 Nitrides	p. 728
15.3.3 Oxynitrides	p. 730
15.3.4 Carbonitrides	p. 733
15.4 Transition Metal Chalcogenides for the ORR	p. 734
15.5 Metal Oxides for the ORR	p. 742
15.6 Conclusions	p. 748
References	p. 748
16 CO-tolerant Catalysts	p. 759
16.1 Introduction	p. 759
16.2 Mechanisms of CO Tolerance	p. 764
16.2.1 Electrochemistry of Carbon Monoxide and Hydrogen	p. 766
16.2.2 Characteristics of PEMFC CO Poisoning	p. 770
16.2.3 Bifunctional Mechanism of CO Tolerance	p. 771
16.2.4 Direct Mechanism of CO Tolerance (Ligand or Electronic Effect)	p. 773
16.2.5 Surface Science Study and Modeling of CO-tolerance Mechanism	p. 774
16.3 Development of CO-tolerant Catalysts	p. 781
16.3.1 PtRu Binary System	p. 783
16.3.2 PtMo Binary System	p. 787
16.3.3 PtSn Binary System	p. 790
16.3.4 PtM (M = Fe, Co, Ni, Ta, Rh, Pd) Binary Systems	p. 791
16.3.5 PtRuM (M = Mo, Sn, W, Cr, Zr, Nb, Ag, Au, Rh, Os, and Ta) Ternary Systems	p. 794
16.3.6 The Pt, PtRu-MO x (M = Mo, W, and V) System	p. 796
16.3.7 Ru-modified Pt Catalysts and Pt-modified Ru Catalysts	p. 799
16.3.8 PtRu on Functionalized Carbon and Carbon Nanotube Systems	p. 802
16.3.9 PtAu Binary System	p. 804
16.3.10 Pt-free Systems	p. 804
16.4 Preparation of CO-tolerant Catalysts	p. 805
16.5 Conclusions	p. 809
References	p. 811
17 Reversal-tolerant Catalyst Layers	p. 835
17.1 Introduction	p. 835
17.2 Cell Voltage Reversal	p. 838
17.2.1 Air Starvation	p. 838
17.2.2 Fuel Starvation	p. 839
17.2.3 Electrocatalyst Degradation in PEM Fuel Cells Caused by Cell Voltage Reversal During Fuel Starvation	p. 842
17.3 Development of Reversal-tolerant Catalyst Layers	p. 845
17.3.1 Reversal Tolerance Cathode Catalyst Layer	p. 846
17.3.2 Reversal Tolerance Anode Catalyst Layer	p. 847
17.4 Conclusions	p. 856
References	p. 856
18 High-temperature PEM Fuel Cell Catalysts and Catalyst Layers	p. 861
18.1 Opportunities and Challenges for High-temperature PEM Fuel Cells	p. 861
18.1.1 Advantages of High-temperature PEM Fuel Cells	p. 861
18.1.2 Routes to Increase the Operating Temperature	p. 867
18.1.3 Challenges of Catalysts/Catalyst Layers	p. 867
18.2 Catalysts for High-temperature PEM Fuel Cells	p. 868
18.2.1 Current Research Activities	p. 868
18.2.2 Degradation of Catalysts at High Temperatures	p. 869
18.2.3 Catalyst Support Strategy to Improve High-temperature Catalysts/Catalyst Layers	p. 876
18.2.4 High-temperature Catalyst Layers - Components and Structure	p. 877
18.2.5 Strategies for HT Catalyst/Catalyst Layer Performance Improvement and Mitigation	p. 878
18.2.6 Suggestions for Future Work	p. 878
18.2.7 Typical Example Analysis	p. 878
18.3 Summary	p. 884
References	p. 884
19 Conventional Catalyst Ink, Catalyst Layer and MEA Preparation	p. 889
19.1 Introduction	p. 889
19.2 Principles of Gas Diffusion Electrodes and MEA Structure	p. 889
19.3 Catalyst Layer	p. 893
19.3.1 Preparation of Catalyst Ink	p. 893
19.3.2 Preparation of the Catalyst Layer	p. 895
19.4 Preparation of the MEA	p. 911
19.5 Summary and Outlook	p. 911
References	p. 912
20 Spray-based and CVD Processes for Synthesis of Fuel Cell Catalysts and Thin Catalyst Layers	p. 917
20.1 Introduction	p. 917
20.2 Spray Pyrolysis Approach	p. 919
20.2.1 Current Research Activities	p. 919
20.2.2 Spray Conversion and Aerosol Routes for Powder Manufacturing	p. 919
20.2.3 Pt Nanoparticle Preparation via Spray Route	p. 921
20.2.4 Morphology of Catalyst Deposited by Spray Pyrolysis	p. 922
20.2.5 Electrochemical Performance	p. 925
20.2.6 Electrocatalytic Activity and Stability of Pt-based Catalysts	p. 926
20.2.7 Typical Example Analysis	p. 928
20.3 Deposition of Catalyst Layer by CVD	p. 929
20.3.1 Current Research Activities	p. 930
20.3.2 Film Formation from Vapor Phase by CVD	p. 931
20.3.3 Morphological and Microstructural Stability	p. 933
20.3.4 Electrochemical Performance and Catalytic Activity	p. 935
20.3.5 Typical Examples Analysis	p. 939
20.4 Flame-based Processing	p. 941
20.4.1 Current Research Activities	p. 942
20.4.2 Atomization Process	p. 943
20.4.3 Particle Formation in the Flame	p. 944
20.4.4 Particle Size Control	p. 946
20.4.5 Electrochemical Performance and Catalytic Activity of the Flame Deposited Catalyst	p. 950
20.4.6 Typical Examples Analysis	p. 954
20.5 Summary	p. 958
References	p. 958
21 Catalyst Layer/MEA Performance Evaluation	p. 965
21.1 Introduction	p. 965
21.2 Theoretical Analysis	p. 966
21.2.1 Open Circuit Voltage (OCV) of the PEMFC	p. 966
21.2.2 Exchange Current Density, i 0	p. 968
21.2.3 Tafel Slope, b	p. 968
21.2.4 Polarization Curve Analysis	p. 971
21.3 Physical Chemistry Evaluation of Catalyst Layer	p. 973
21.3.1 Pore Structure Analysis of Catalyst Layer	p. 973
21.3.2 Protonic and Electronic Conductivity in the Catalyst Layer	p. 974
21.3.3 Wettability of the Catalyst Layer	p. 975
21.4 Catalyst Layer Evaluation in a Half-cell	p. 978
21.4.1 Rotating Disk Electrode (RDE) Test	p. 978
21.4.2 Cyclic Voltammetry (CV) Test	p. 981
21.4.3 Polarization Curves in a Half-cell	p. 984
21.5 MEA Evaluation by the Single-cell Test	p. 986
21.5.1 Test Station	p. 986
21.5.2 Polarization Curve	p. 988
21.5.3 Resistance Test - AC Impedance Test	p. 988
21.5.4 Permeability/Crossover Test	p. 992
21.6 Lifetime/Durability Testing of the MEA	p. 994
21.6.1 Mechanisms of MEA Degradation	p. 994
21.6.2 Durability Testing	p. 996
21.7 Conclusions	p. 997
References	p. 997
22 Catalyst Layer Composition Optimization	p. 1003
22.1 Catalyst Layer Materials Selection and Evaluation	p. 1003
22.1.1 Catalyst selection	p. 1003
22.1.2 Gas Diffusion Layer (GDL) and Microporous Layer (MPL) Materials Selection	p. 1011
22.2 Fabrication Optimization Processes for the Catalyst Layer of MEAs	p. 1016
22.2.1 GDL Substrate Preparation	p. 1016
22.2.2 Microporous Layer (MPL) Preparation and Optimization	p. 1017
22.2.3 Catalyst Ink Composition and Preparation	p. 1019
22.2.4 Carbon-supported Catalyst Layer Fabrication	p. 1023
22.2.5 Pt Catalyst Layer Fabrication	p. 1027
22.2.6 MEA Fabrication and Optimization	p. 1029
22.3 MEA Performance Verification with its Catalyst Layer Fabrication Optimization Process	p. 1031
22.3.1 MEA Performance Characterization	p. 1031
22.3.2 MEA Water Management Characterization	p. 1032
22.3.3 MEA CO and Other Contamination Tolerance	p. 1032
22.3.4 MEA Lifetime Enhancement via MEA Fabrication Process Improvement	p. 1033
References	p. 1033
23 Catalyst Layer Degradation, Diagnosis and Failure Mitigation	p. 1041
23.1 Introduction	p. 1041
23.2 Diagnosis of Catalyst Layer Degradation: Fuel Cell Failure Analysis	p. 1044
23.2.1 Diagnostic Tools to Identify Catalyst Degradation During Fuel Cell Operation: Electrochemical Methods	p. 1045
23.2.2 Ex situ Tools for Characterization of Catalyst Degradation During Fuel Cell Operation	p. 1049
23.2.3 Durability and Accelerated Stress Testing	p. 1054
23.3 Anode Catalyst Layer Degradation	p. 1056
23.3.1 Anode Catalyst Layer Degradation Caused by Contamination	p. 1056
23.3.2 Anode Catalyst Layer Degradation-Voltage Reversal	p. 1061
23.3.3 Ru Leaching and Crossover	p. 1064
23.4 Cathode Catalyst Layer Degradation	p. 1066
23.4.1 Platinum Dissolution During Fuel Cell Operation	p. 1066
23.4.2 Pt Accumulation and Distribution in the Membrane after Fuel Cell Operation	p. 1073
23.4.3 Loss of Platinum Surface Area Due to Agglomeration	p. 1075
23.4.4 Carbon Corrosion of Catalyst Layer	p. 1080
23.5 Summary	p. 1087
References	p. 1089
Acronyms and Abbreviations	p. 1095
Contributor Biographies	p. 1103
Author Index	p. 1117
Subject Index	p. 1119

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