Electrocatalysis for Membrane Fuel Cells

Nicolas Alonso-Vante is emeritus Professor since September 2021 at the University of Poitiers, France. In the field of materials science, electrocatalysis and photoelectrocatalysis, he has authored over 250 peer-reviewed publications, book chapters, editor of a two-volume e-book on electrochemistry in Spanish, author of two books and six patents, with more than 10320 citations and an h-index of 55 (ResearchGate). He has received the awards of the National Polytechnic Institute-Mexico as an R&D distinguished graduate, the Mexican Council of Technology SNI-III recognition as a Mexican researcher working outside Mexico, and has been awarded the NM Emanuel Medal from the Russian Academy of Science. Vito Di Noto is Full Professor of Electrochemistry for Energy and Solid-State Chemistry in the Department of Industrial Engineering of the University of Padova, Italy. He is Fellow of the Electrochemical Society, Past-President of the Electrochemical Division of the Italian Chemical Society and the recipient of the “Energy Technology Division Award” of The Electrochemical Society. In the field of advanced functional materials for electrochemical energy conversion and storage device, he is author of more than 335 international publications, with more than 9200 citations and an h-index of 54 (Google Scholar). He is inventor of more than 30 international patents.

• Preface xvPart I Overview of Systems 11 System-level Constraints on Fuel Cell Materials and Electrocatalysts 3Elliot Padgett and Dimitrios Papageorgopoulos1.1 Overview of Fuel Cell Applications and System Designs 31.1.1 System-level Fuel Cell Metrics 31.1.2 Fuel Cell Subsystems and Balance of Plant (BOP) Components 51.1.3 Comparison of Fuel Cell Systems for Different Applications 91.2 Application-derived Requirements and Constraints 101.2.1 Fuel Cell Performance and the Heat Rejection Constraint 101.2.2 Startup, Flexibility, and Robustness 131.2.3 Fuel Cell Durability 141.2.4 Cost 161.3 Material Pathways to Improved Fuel Cells 181.4 Note 19Acronyms 20Symbols 20References 202 PEM Fuel Cell Design from the Atom to the Automobile 23Andrew Haug and Michael Yandrasits2.1 Introduction 232.2 The PEMFC Catalyst 272.3 The Electrode 322.4 Membrane 382.5 The GDL 422.6 CCM and MEA 462.7 Flowfield and Single Fuel Cell 502.8 Stack and System 55Acronyms 57References 58Part II Basics – Fundamentals 693 Electrochemical Fundamentals 71Vito Di Noto, Gioele Pagot, Keti Vezzù, Enrico Negro, and Paolo Sgarbossa3.1 Principles of Electrochemistry 713.2 The Role of the First Faraday Law 713.3 Electric Double Layer and the Formation of a Potential Difference at the Interface 733.4 The Cell 743.5 The Spontaneous Processes and the Nernst Equation 753.6 Representation of an Electrochemical Cell and the Nernst Equation 773.7 The Electrochemical Series 793.8 Dependence of the E cell on Temperature and Pressure 823.9 Thermodynamic Efficiencies 833.10 Case Study – The Impact of Thermodynamics on the Corrosion of Low-T FC Electrodes 853.11 Reaction Kinetics and Fuel Cells 883.11.1 Correlation Between Current and Reaction Kinetics 883.11.2 The Concept of Exchange Current 893.12 Charge Transfer Theory Based on Distribution of Energy States 893.12.1 The Butler–Volmer Equation 963.12.2 The Tafel Equation 1003.12.3 Interplay Between Exchange Current and Electrocatalyst Activity 1013.13 Conclusions 103Acronyms 104Symbols 104References 1074 Quantifying the Kinetic Parameters of Fuel Cell Reactions 111Viktoriia A. Saveleva, Juan Herranz, and Thomas J. Schmidt4.1 Introduction 1114.2 Electrochemical Active Surface Area (ECSA) Determination 1144.2.1 ECSA Determination Using Underpotential Deposition 1154.2.1.1 Hydrogen Underpotential Deposition (H UPD) 1164.2.1.2 Copper Underpotential Deposition (Cu UPD) 1174.2.2 ECSA Quantification Based on the Adsorption of Probe Molecules 1184.2.2.1 CO Stripping 1184.2.2.2 No –2 ¨MNO Sorption 1194.2.3 Double-layer Capacitance Measurements and Other Methods 1204.2.4 ECSA Measurements in a PEFC: Which Method to Choose? 1204.3 H 2 -Oxidation and Electrochemical Setups for the Quantification of Kinetic Parameters 1214.3.1 Rotating Disc Electrodes (RDEs) 1224.3.2 Hydrogen Pump (PEFC) Approach 1244.3.3 Ultramicroelectrode Approach 1254.3.4 Scanning Electrochemical Microscopy (SECM) Approach 1254.3.5 Floating Electrode Method 1274.3.6 Methods Summary 1284.4 ORR Kinetics 1294.4.1 ORR Mechanism Studies with RRDE Setups 1294.4.2 ORR Pathway on Me/N/C ORR Catalysts 1304.4.3 ORR Kinetics: Methods 1324.4.3.1 Pt-based Electrodes 1324.4.3.2 Pt-free Catalysts: RDE vs. PEFC Kinetic Studies 1334.5 Concluding Remarks 133Acronyms 134Symbols 134References 1355 Adverse and Beneficial Functions of Surface Layers Formed on Fuel Cell Electrocatalysts 149Shimshon Gottesfeld5.1 Introduction 1495.2 Catalyst Capping in Heterogeneous Catalysis and in Electrocatalysis 1515.3 Passivation of PGM/TM and Non-PGM HOR Catalysts and Its Possible Prevention 1565.4 Literature Reports on Fuel Cell Catalyst Protection by Capping 1615.4.1 Protection of ORR Pt catalysts Against Agglomeration by an Ultrathin Overlayer of Mesoporous SiO 2 or Me–SiO 2 1615.4.2 Protection by Carbon Caps Against Catalyst Detachment and Catalyst Passivation Under Ambient Conditions 1625.5 Other Means for Improving the Performance Stability of Supported Electrocatalysts 1665.5.1 Replacement of Carbon Supports by Ceramic Supports 1665.5.2 Protection of Pt Catalysts by Enclosure in Mesopores 1675.6 Conclusions 170Abbreviations 171References 171Part III State of the Art 1756 Design of PGM-free ORR Catalysts: From Molecular to the State of the Art 177Naomi Levy and Lior Elbaz6.1 Introduction 1776.2 The Influence of Molecular Changes Within the Complex 1796.2.1 The Role of the Metal Center 1796.2.2 Addition of Substituents to MCs 1836.2.2.1 Beta-substituents 1846.2.3 Meso-substituents 1866.2.4 Axial Ligands 1876.3 Cooperative Effects Between Neighboring MCs 1906.3.1 Bimetallic Cofacial Complexes – “Packman” Complexes 1916.3.2 MC Polymers 1916.4 The Physical and/or Chemical Interactions Between the Catalyst and Its Support Material 1936.5 Effect of Pyrolysis 194Acronyms 196References 1967 Recent Advances in Electrocatalysts for Hydrogen Oxidation Reaction in Alkaline Electrolytes 205Indra N. Pulidindi and Meital Shviro7.1 Introduction 2057.2 Mechanism of the HOR in Alkaline Media 2067.3 Electrocatalysts for Alkaline HOR 2127.3.1 Platinum Group Metal HOR Electrocatalysts 2127.3.2 Non-platinum Group Metal-based HOR Electrocatalysts 2147.4 Conclusions 220Acronyms 221References 2218 Membranes for Fuel Cells 227Paolo Sgarbossa, Giovanni Crivellaro, Francesco Lanero, Gioele Pagot, Afaaf R. Alvi, Enrico Negro, Keti Vezzù, and Vito Di Noto8.1 Introduction 2278.2 Properties of the PE separators 2288.2.1 Benchmarking of IEMs 2298.2.2 Ion-exchange Capacity (IEC) 2298.2.3 Water Uptake (WU), Swelling Ratio (SR), and Water Transport 2318.2.4 Ionic Conductivity (σ) 2338.2.5 Gas Permeability 2348.2.6 Chemical Stability 2358.2.7 Thermal and Mechanical Stability 2378.2.8 Cost of the IEMs 2398.3 Classification of Ion-exchange Membranes 2408.3.1 Cation-exchange Membranes (CEMs) 2408.3.1.1 Perfluorinated Membranes 2408.3.1.2 Nonperfluorinated Membranes 2458.3.2 Anion-exchange Membranes (AEMs) 2468.3.2.1 Functionalized Polyketones 2478.3.2.2 Poly(Vinyl Benzyl Trimethyl Ammonium) (PVBTMA) Polymers 2488.3.2.3 Poly(sulfones) (PS) 2498.3.3 Hybrid Ion-exchange Membranes 2498.3.3.1 Hybrid Membranes with Single Ceramic Oxoclusters [P/(M X O Y) n] 2508.3.3.2 Hybrid Membranes Comprising Surface-functionalized Nanofillers 2548.3.3.3 Hybrid Membranes Doped with hierarchical “Core–Shell” Nanofillers 2548.3.4 Porous Membranes 2578.3.4.1 Porous Membranes as Host Material 2578.3.4.2 Porous Membranes as Support Layer 2588.3.4.3 Porous Membranes as Unconventional Separators 2598.4 Mechanism of Ion Conduction 2598.5 Summary and Perspectives 268Acronyms 271Symbols 272References 2729 Supports for Oxygen Reduction Catalysts: Understanding and Improving Structure, Stability, and Activity 287Iwona A. Rutkowska, Sylwia Zoladek, and Pawel J. Kulesza9.1 Introduction 2879.2 Carbon Black Supports 2889.3 Decoration and Modification with Metal Oxide Nanostructures 2899.4 Carbon Nanotube as Carriers 2919.5 Doping, Modification, and Other Carbon Supports 2939.6 Graphene as Catalytic Component 2939.7 Metal Oxide-containing ORR Catalysts 2969.8 Photodeposition of Pt on Various Oxide–Carbon Composites 2999.9 Other Supports 3019.10 Alkaline Medium 3029.11 Toward More Complex Hybrid Systems 3039.12 Stabilization Approaches 3069.13 Conclusions and Perspectives 307Acknowledgment 308Acronyms 308References 308Part IV Physical–Chemical Characterization 31910 Understanding the Electrocatalytic Reaction in the Fuel Cell by Tracking the Dynamics of the Catalyst by X-ray Absorption Spectroscopy 321Ditty Dixon, Aiswarya Bhaskar, and Aswathi Thottungal10.1 Introduction 32110.2 A Short Introduction to XAS 32310.3 Application of XAS in Electrocatalysis 32510.3.1 Ex Situ Characterization of Electrocatalyst 32510.3.2 Operando XAS Studies 33010.4 Δμ XANES Analysis to Track Adsorbate 33410.5 Time-resolved Operando XAS Measurements in Fuel Cells 33810.6 Fourth-generation Synchrotron Facilities and Advanced Characterization Techniques 34010.6.1 Total-reflection Fluorescence X-ray Absorption Spectroscopy 34110.6.2 Resonant X-ray Emission Spectroscopy (RXES) 34110.6.3 Combined XRD and XAS 34210.7 Conclusions 342Acronyms 343References 344Part V Modeling 34911 Unraveling Local Electrocatalytic Conditions with Theory and Computation 351Jun Huang, Mohammad J. Eslamibidgoli, and Michael H. Eikerling11.1 Local Reaction Conditions: Why Bother? 35111.2 From Electrochemical Cells to Interfaces: Basic Concepts 35211.3 Characteristics of Electrocatalytic Interfaces 35511.4 Multifaceted Effects of Surface Charging on the Local Reaction Conditions 35611.5 The Challenges in Modeling Electrified Interfaces using First-principles Methods 35811.5.1 Computational Hydrogen Electrode 35911.5.2 Unit-cell Extrapolation, Explicit Solvated Protons, and Excess Electrons 36011.5.3 Counter Charge and Reference Electrode 36111.5.4 Effective Screening Medium and mPB Theory 36111.5.5 Grand-canonical DFT 36211.6 A Concerted Theoretical–Computational Framework 36211.7 Case Study: Oxygen Reduction at Pt(111) 36411.8 Outlook 367Acronyms 367Symbols 368References 368Part VI Protocols 37512 Quantifying the Activity of Electrocatalysts 377Karla Vega-Granados and Nicolas Alonso-Vante12.1 Introduction: Toward a Systematic Protocol for Activity Measurements 37712.2 Materials Consideration 37812.2.1 PGM Group 37812.2.2 Low PGM and PGM-free Approaches 37912.2.3 Impact of Support Effects on Catalytic Sites 38112.3 Electrochemical Cell Considerations 38212.3.1 Cell Configuration and Material 38212.3.2 Electrolyte 38512.3.2.1 Purity 38512.3.2.2 Protons vs. Hydroxide Ions 38612.3.2.3 Influence of Counterions 38812.3.3 Electrode Potential Measurements 38812.3.4 Preparation of Electrodes 39112.3.5 Well-defined and Nanoparticulated Objects 39512.4 Parameters Diagnostic of Electrochemical Performance 39612.4.1 Surface Area 39612.4.2 Hydrogen Underpotential Deposition Integration 39712.4.2.1 Surface Oxide Reduction 39812.4.2.2 CO Monolayer Oxidation (CO Stripping) 40012.4.2.3 Underpotential Deposition of Metals 40112.4.2.4 Double-layer Capacitance 40212.4.3 Electrocatalysts Site Density 40212.4.4 Data Evaluation (Half-Cell Reactions) 40412.4.5 The E 1/2 and E (j Pt (5%)) Parameters 40512.5 Stability Tests 40712.6 Data Evaluation (Auxiliary Techniques) 40912.6.1 Surface Atoms vs. Bulk 41012.7 Conclusions 411Acknowledgments 412Acronyms 412Symbols 413References 41413 Durability of Fuel Cell Electrocatalysts and Methods for Performance Assessment 429Bianca M. Ceballos and Piotr Zelenay13.1 Introduction 42913.2 Fuel Cell PGM-free Electrocatalysts for Low-temperature Applications 43113.3 PGM-free Electrocatalyst Degradation Pathways 43213.3.1 Demetallation 43213.3.2 Carbon Oxidation 43613.3.3 Micropore Flooding 43913.3.4 Nitrogen Protonation and Anionic Adsorption 43913.4 PGM-free Electrocatalyst Durability and Metrics 44013.4.1 Performance and Durability Evaluation in Air-supplied Fuel Cell Cathode 44013.4.2 Assessment of Carbon Corrosion in Nitrogen-purged Cathode 44313.4.3 Determination of Performance Loss upon Cycling Cathode Catalyst in Nitrogen 44313.4.4 Recommendations for ORR Electrocatalyst Evaluation in RRDE in O 2 and in an Inert Gas 44613.4.5 Electrocatalyst Corrosion 44713.5 Low-PGM Catalyst Degradation 44713.5.1 Pt Dissolution 44913.5.2 Carbon Support Corrosion 45213.5.3 Pt Catalyst MEA Activity Assessment and Durability 45413.5.4 PGM Electrocatalyst MEA Conditioning in H 2 /Air 45413.5.5 Accelerated Stress Test of PGM Electrocatalyst Durability 45613.6 Conclusion 457Acronyms 459References 460Part VII Systems 47114 Modeling of Polymer Electrolyte Membrane Fuel Cells 473Andrea Baricci, Andrea Casalegno, Dario Maggiolo, Federico Moro, Matteo Zago, and Massimo Guarnieri14.1 Introduction 47314.2 General Equations for PEMFC Models 47414.2.1 Analytical and Numerical Modeling 47414.2.2 Reversible Electromotive Force 47614.2.3 Fuel Cell Voltage 47714.2.4 Activation Overpotential 47814.2.5 Ohmic Overpotential – PEM Model 47914.2.6 Concentration Overpotential 48014.2.7 Examples of Fuel Cell Modeling 48214.3 Multiphase Water Transport Model for PEMFCs 48314.4 Fluid Mechanics in PEMFC Porous Media: From 3D Simulations to 1D Models 48814.4.1 From Micro- to Macroscopic Models 49014.4.2 Porous Medium Anisotropy 49114.4.3 Fluid–Fluid Viscous Drag 49214.4.4 Surface Tension and Capillary Pressure 49214.5 Physical-based Modeling for Electrochemical Impedance Spectroscopy 49614.5.1 Experimental Measurement and Modeling Approaches 49614.5.2 Physical-based Modeling 49714.5.2.1 Current Relaxation 49714.5.2.2 Laplace Transform 49814.5.3 Typical Impedance Features of PEMFC 49814.5.4 Application of EIS Modeling to PEMFC Diagnostic 50014.5.5 Approximations of 1D Approach 50114.6 Conclusions and Perspectives 502Acronyms 503Symbols 504References 50715 Physics-based Modeling of Polymer Electrolyte Membrane Fuel Cells: From Cell to Automotive Systems 511Andrea Baricci, Matteo Zago, Simone Buso, Marco Sorrentino, and Andrea Casalegno15.1 Polymer Fuel Cell Model for Stack Simulation 51115.1.1 General Characteristics of a Fuel Cell System for Automotive Applications 51115.1.2 Analysis of the Channel Geometry for Stack Performance Modeling 51415.1.3 Analysis of the Air and Hydrogen Utilization for Stack Performance Modeling 51615.1.4 Introduction to Transient Stack Models 51815.2 Auxiliary Subsystems Modeling 51915.2.1 Air Management Subsystem 51915.2.2 Hydrogen Management Subsystem 52115.2.3 Thermal Management Subsystem 52215.2.4 PEMFC System Simulation 52215.3 Electronic Power Converters for Fuel Cell-powered Vehicles 52515.3.1 Power Converter Architecture 52715.3.2 Load Adaptability 52715.3.3 Power Electronic System Components 52815.3.3.1 Port Interface Converters 53015.3.3.2 The PEMFC Interface Converter 53015.3.3.3 The Motor Interface Converter 53015.3.3.4 The Energy Storage Interface 53115.3.3.5 Supervisory Control 53115.4 Fuel Cell Powertrains for Mobility Use 53215.4.1 Transport Application Scenarios 53215.4.2 Tools for the Codesign of Transport Fuel Cell Systems and Energy Management Strategies 53415.4.2.1 Automotive Case Study: Optimal Codesign of an LDV FCHV Powertrain 535Acronyms 540Symbols 541References 541Index 545