Conversion of Water and CO2 to Fuels using Solar Energy

Oomman K. Varghese, PhD, is an Associate Professor in the Department of Physics, Researcher at Texas Center for Superconductivity and Leader of Nanomaterials and Devices Laboratory at the University of Houston. In 2011, Thomson Reuters ranked him 9th among “World’s Top 100 Materials Scientists” in the previous decade. Flavio L. Souza, PhD, is the Lead Researcher and Coordinator of Green Hydrogen Program of Brazilian Center for Research in Energy and Materials (CNPEM), Associate Professor at Federal University of ABC and an accredited researcher by CNPq (The Brazilian Research Council). He received an Academic Excellence award (2017) from Federal University of ABC for his achievements in research and dedication to higher education.

• List of Contributors xiiiPreface xvii1 Solar Fuel Generation: The Relevance and Approaches 1Ingrid Rodriguez-Gutierrez, Flavio L. Souza, and Oomman K. Varghese1.1 Introduction 11.2 The Nexus Between Fossil Fuels, Global Warming, and Climate Change 21.3 The Energy System Transformation 41.4 Solar Fuels 51.5 Solar Reduction of CO 2 forFuelProduction 61.6 Solar Water Splitting for H 2 Generation 71.7 Solar to Fuel Conversion Pathways 81.7.1 Bioconversion 81.7.2 Thermoconversion 91.7.3 Electroconversion 101.7.4 Photoconversion 121.8 Conclusion 13References 13Section 1 Solar Fuel Generation Processes: Science and Technology 192 Introduction to Photocatalytic/Photoelectrochemical Fuel Generation: Science and Technology Perspective 21Ke Fan, Lei Wang, and Lianpeng Tong2.1 Introduction 212.2 The Natural Photosynthetic Water Splitting and CO 2 Reduction 222.2.1 Oxygen-Evolving Complex (OEC) 222.2.2 Hydrogenase 232.2.3 Enzymes that Reduce CO 2 242.3 Artificial Systems for Solar-Driven Chemical Fuels Production 252.3.1 Bioinspired Synthetic Systems 252.3.1.1 Synthetic Molecular Catalysts 252.3.1.2 Application of Synthetic Model Compounds in PEC Cells 262.3.2 Bioinorganic Hybrid Systems 262.3.3 Photoelectrochemical Water Splitting and CO 2 Reduction 272.3.3.1 Some Basic Concepts of Semiconductors 272.3.3.2 Photoelectrochemical (PEC) Water Splitting 292.3.3.3 Configurations of PEC Cell for Water Splitting 332.3.3.4 A Few Semiconductors Extensively Studied for Water Splitting 342.3.3.5 Photoelectrochemical (PEC) CO 2 reduction 352.3.3.6 Particulate Photocatalytic Systems for Water Splitting/CO 2 Reduction 372.4 Challenges and Outlook 39References 403 Solar Thermochemical Fuels 47Christoph FalterNomenclature 473.1 Thermodynamics 483.2 Solar Thermochemical Processes and Reactor Concepts 493.2.1 Thermolysis of H 2 O 493.2.2 H 2 /CO From H 2 O/CO 2 Using Thermochemical Cycles 503.3 Energy and Mass Balance 543.3.1 Thermochemical Reactor 543.3.2 Energy and Mass Balance of Solar Thermochemical Fuel Plant 553.3.3 Possibilities of Enhancing Plant Efficiency 573.4 Techno-Economic Analysis 583.4.1 System Description 593.4.2 Economic Model 593.4.3 Production Costs 603.4.4 Comparison with Other Alternative Fuel Pathways 623.5 Life-Cycle Analysis 633.5.1 Goal and Scope 633.5.2 Inventory Analysis 643.5.3 Impact Assessment 643.5.4 Interpretation 653.5.4.1 Scenario Analysis–CO 2 From Natural Gas Combustion 653.5.4.2 Scenario Analysis–Grid Electricity 653.5.4.3 Comparison with Published GWP Values of Other Fuel Pathways 663.6 Land and Water Demand 673.6.1 Water Footprint 673.6.2 Land Demand 693.7 Geographical Potential 713.7.1 Determination of Suitable Areas for Solar Thermochemical Fuel Production 713.7.2 Determination of Life-Cycle Production Costs 733.7.3 Production Cost 743.8 Conclusions 76References 774 Principles, Operations, and Techno-Economics of Photovoltaic-Electrolysis and Photoelectrochemical Water Splitting Processes 83Nicolas Gaillard4.1 Introduction 834.2 The Solar-to-Hydrogen Conversion Process 854.2.1 Fundamental Concepts 854.2.2 Material and Device Considerations 864.3 PV-Electrolysis Water Splitting 884.3.1 The Photovoltaic Process 884.3.2 Fundamentals of Water Electrolysis 914.3.3 PV-E Operating Principles 934.3.4 Evolution of PV-E Systems and Current State-of-the-Art 944.3.4.1 PV-E Systems with Planar Photovoltaics 944.3.4.2 PV-E Systems with Concentrated Photovoltaics 964.4 Photoelectrochemical Water Splitting 974.4.1 Energetics of the Semiconductor/Liquid Junction 974.4.2 Charge Transfer Dynamics at the Semiconductor/Liquid Junction 994.4.3 Current–Potential Behavior of a Photoelectrode 1004.4.4 Spontaneous Water Splitting with Multi-Junction PEC Devices 1034.5 Techno-Economics of PV-E and PEC Water Splitting 1074.5.1 Similarities and Differences Between PV-E and PEC Water Splitting Technologies 1074.5.2 Independent Assessments of PEC Technologies 1084.5.3 Independent Assessments of PV-E Technology 1104.5.4 Comparative Assessments of PV-E and PEC Technologies 1104.6 Conclusion and Outlook 111Acknowledgments 112References 1135 A Brief History of Molecular Photosynthesis: The Quest for the Bridge Between Light and Chemistry 119Liniquer A. Fontana, Vitor H. Rigolin, Catia Ornelas, and Jackson D. Megiatto Jr.5.1 Introduction 1195.2 Historical Context and Early Findings 1195.3 The Beginning of the Modern Understanding of Photosynthesis 1215.4 Molecular Photosynthesis: Human Ingenuity Enters the Game 1235.4.1 Biomimetic Reaction Centers 1235.4.2 Artificial Reaction Centers with Nonnatural Electron Donors and Acceptors 1265.4.3 Supramolecular Assembly of Artificial Reaction Centers 1285.4.4 Artificial Antenna 1315.4.5 Photo-Regulation 1325.4.6 Artificial Reaction Centers Thermodynamically Poised to Oxidize Water 1345.5 Harvesting the Energy of Charge-Separated States for Solar Fuel Production 1375.5.1 Solar-Sensitized Photoelectrochemical Cells 1375.5.2 Artificial Leaf 1385.6 Conclusions 139References 1396 The Competitive Kinetics of Solar-Driven CO 2 Reduction 143Mark T. Spitler6.1 Introduction 1436.2 Photosynthetic Systems 1446.2.1 General 1446.2.2 PSII Coupling to the OEC 1466.2.3 PSI Coupling to PSII and RuBisCO 1486.2.4 LHC Coupling 1496.2.5 Indirect Coupling to RuBisCo 1496.2.6 Photostability 1506.3 Water Oxidation 1516.3.1 Molecular Water Oxidation 1526.3.2 Dye-Sensitized Photoelectrosynthesis Cell (DSPEC) 1546.3.3 Photoelectrochemical (PEC) Water Splitting 1586.3.4 Particles 1606.4 CO 2 Reduction 1636.4.1 Recycling Applications 1636.4.2 Metals as Catalysts 1646.4.3 PV-Driven CO 2 Reduction 1666.4.4 Solar Fuel Harvesting 1676.4.5 Semiconductor Photoanode-Driven Reduction of CO 2 at Metals 1676.4.6 Semiconductor Electrodes 1676.4.7 Reduction of CO 2 at Semiconductor Surfaces 1696.4.8 Molecular Catalysts 1716.4.9 Particles for CO 2 Reduction 1726.5 Conclusions 174References 1757 Utilizing the Band Diagram Framework to Interpret the Operation of Photoelectrochemical Cells 183Kirk H. Bevan, Botong Miao, and Asif Iqbal7.1 Semiconductor Concepts 1837.2 Semiconductor–Liquid Junctions in the Dark 1867.2.1 Charge Equilibration in the Dark 1877.2.2 Semiconductor–Liquid Junctions Under Bias in the Dark 1887.2.3 Biasing with Respect to Reference Electrodes 1907.3 Illuminated Semiconductor–Liquid Junctions 1907.3.1 Gartner’s Model 1907.3.2 Peter’s Model 1937.4 The Role of Numerical Modeling 1947.4.1 Semiclassical Approach 1947.4.2 Insights from Semiclassical Modeling 1977.5 Outlook 200References 200Section 2 Materials for Solar Fuel Generation 2038 Materials Used for Solar Thermal/Thermochemical Processes for CO 2 /H 2 O Dissociation/Conversion 205Heng Pan, Youjun Lu, and Bingchan Hu8.1 Introduction 2058.2 Solar Thermolysis of H 2 OorCO 2 2058.3 Redox Pairs for Two-Step Thermochemical Cycles 2068.3.1 Volatile Redox Pairs 2078.3.1.1 ZnO/Zn Pair 2078.3.1.2 SnO 2 /SnO Pair 2098.3.2 Nonvolatile Redox Pairs 2098.3.2.1 Fe 3 O 4 /FeO Pair 2098.3.2.2 CeO 2 /CeO 2−δ Pairs 2108.3.2.3 CoFe 2 O 4 /FeAl 2 O 4 Pairs 2118.3.2.4 Perovskites 2118.3.3 Redox Pairs: New Discoveries 2128.4 Materials for Sulfur–Iodine (S–I) Cycle 2138.4.1 Corrosion-Resistant Materials 2148.4.2 The Catalysts of HI Decomposition 2148.4.3 The Catalysts for H 2 SO 4 Decomposition 2178.5 Other Multi-Step Thermochemical Cycles 2188.6 Catalysts for Solar Gasification and Reforming 2208.6.1 Catalysts for Solar Gasification 2208.6.2 Catalysts for Solar Reforming of Methane 2208.6.3 Catalysts for Solar Reforming of Methanol 2218.7 Summary and Outlook 222Acknowledgment 222Conflict of Interest 222References 2229 Electrocatalytic Reduction of CO 2 to Value-Added Chemicals and Fuels 233Qian Sun, Kamran Dastafkan, and Chuan Zhao9.1 Introduction 2339.2 Fundamentals of CO 2 Electroreduction (CO 2 RR) 2359.2.1 Reaction Mechanism of CO 2 RR 2359.2.2 Electrochemical Cells 2379.2.2.1 H-Cell 2379.2.2.2 Flow Cell 2409.2.2.3 Mea 2419.2.2.4 High-Temperature Molten Salt Cell 2429.2.2.5 Solid Oxide Cell 2429.2.3 Electrolytes 2439.3 Electrocatalysts for CO 2 RR 2449.3.1 Metals 2459.3.1.1 Noble Metals 2459.3.1.2 Transition Metals 2479.3.1.3 Oxide-Derived Metals 2489.3.1.4 Metal Alloys 2489.3.2 Metal Compounds 2509.3.2.1 Metal Chalcogenides 2509.3.2.2 Metal Oxides 2529.3.2.3 Metal Nitrides 2539.3.2.4 Metal Hydroxides 2549.3.3 Single-Atom Catalysts 2549.3.3.1 Noble Metal SACs 2549.3.3.2 Transition Metal SACs 2559.3.3.3 Other Metal SACs 2569.3.4 Molecular Catalysts 2579.3.4.1 Organometallic Complexes 2579.3.4.2 MOF and COF Catalysts 2589.3.4.3 Metal-Free and Polymerized Catalysts 2599.4 In Situ Characterizations of Electrocatalysts for CO 2 RR 2609.4.1 In Situ Raman 2609.4.2 In Situ UV–vis Spectroscopy 2629.4.3 In Situ FTIR Spectroscopy 2629.4.4 Operando XAS 2639.5 Summary and Perspectives 2649.5.1 Challenges for CO 2 RR 2659.5.2 Comparison with HER 2659.5.3 Perspectives for CO 2 RR 265References 26910 Ceramic Materials for Photocatalytic/Photoelectrochemical Fuel Generation 285Appu V. Raghu and Takashi Tachikawa10.1 Introduction 28510.2 Photocatalytic/Photoelectrochemical Fuel Generation 28510.2.1 Photon Absorption 28810.2.2 Requirements of Materials Useful as Photocatalysts 28910.3 Metal Oxides as Photocatalysts 29010.3.1 Doping and Surface Treatments 29110.3.2 Long-Term Stability 29210.3.3 Heterostructures 29210.4 Other Ceramic Materials 29510.4.1 Nitrides 29510.4.2 Oxynitrides 29610.4.3 Carbides 29610.4.4 MXenes 29710.5 Challenges 30110.6 Conclusion 301References 30111 Gallium Nitride-Based Artificial Photosynthesis Integrated Devices for Solar Hydrogen Generation and Carbon Dioxide Reduction 309Baowen Zhou, Peng Zhou, Wanjae Dong, and Zetian mi11.1 Introduction 30911.2 Merits of III-Nitride Nanostructures for Artificial Photosynthesis 31011.3 Recent Advances in III-Nitrides for Artificial Photosynthesis 31111.3.1 Solar Water Splitting 31111.3.1.1 Photoelectrochemical Water Splitting 31211.3.1.2 Photocatalytic Overall Water Splitting 31611.3.2 Long-Term Stability Studies 32211.4 GaN-Based APID for CO 2 Reduction 32411.4.1 Photochemical CO 2 RR Toward CH 4 Production 32411.4.2 Photochemical CO 2 RR Reduction Toward CH 3 OH Production 32511.4.3 Photoelectrochemical CO 2 Reduction 32611.4.3.1 Photoelectrochemical CO 2 RR Toward CO/H 2 Production 32611.4.3.2 Photoelectrochemical CO 2 RR Toward HCOOH Production 32711.4.3.3 Photoelectrochemical CO 2 RR Toward CH 4 Production 32911.5 Gallium Nitride-Catalyzed Organic Transformations and N 2 Fixation 33011.6 Summary and Prospects 332Acknowledgment 333Conflict of Interest 333Additional Note 333References 33312 Low-Dimensional Materials for Direct Fuel Generation Assisted by Sunlight 341Muhammad Shuaib Khan and Shaohua Shen12.1 Introduction 34112.2 Unique Properties of Low-Dimensional Materials 34412.2.1 Electronic Properties 34412.2.2 Surface Plasmon Resonance 34412.2.2.1 Charge Transfer Mechanism 34512.2.2.2 Local Electric Field 34612.2.3 Crystal Facets, Kinks, and Edges 34612.2.4 Large Surface Area and Abundant Surface-Active Sites 34712.2.5 Heterostructure Construction 34712.3 Applications of Low-Dimensional Materials 34812.3.1 Water Splitting 34812.3.1.1 0D Materials 35012.3.1.2 1D Materials 35212.3.1.3 2D Materials 35412.3.1.4 Low-Dimensional Heterostructures 35512.3.2 CO 2 Reduction 35912.3.2.1 0D Materials 35912.3.2.2 1D Materials 36112.3.2.3 2D Materials 36312.3.2.4 Low-Dimensional Heterostructures 36512.4 Summary and Future Perspective 368Acknowledgments 368References 368Index 377