Preface xi 1 Application of Mössbauer Spectroscopy to Energy Materials 1 Pierre-Emmanuel Lippens, Jean-Claude Jumas, and Josette Olivier-Fourcade 1.1 Introduction 1 1.2 Mössbauer Spectroscopy for Li-ion and Na-ion Batteries 2 1.2.1 Characterization of Electrode Materials and Electrochemical Reactions 2 1.2.2 Tin-Based Negative Electrode Materials for Li-ion Batteries 3 1.2.2.1 Electrochemical Reactions of Lithium with Tin 3 1.2.2.2 Tin Oxides 7 1.2.2.3 Tin Borophosphates 10 1.2.2.4 Tin-Based Intermetallics 13 1.2.3 Iron-Based Electrode Materials 17 1.2.3.1 LiFePO4 as Positive Electrode Material for Li-ion Batteries 17 1.2.3.2 Fe 1.19 PO4 (OH) 0.57 (H2 O) 0.43 /C as Positive Electrode Material for Li-ion Batteries 18 1.2.3.3 Na 1.5 Fe 0.5 Ti 1.5 (PO4) 3 /C as Electrode Material for Na-ion Batteries 19 1.3 Mössbauer Spectroscopy of Tin-Based Catalysts 21 1.3.1 Reforming Catalysis 21 1.3.2 Redox Properties of Pt-Sn Based Catalysts 22 1.3.3 Trimetallic Pt-Sn-In Based Catalysts 24 1.4 Conclusion 26 Acknowledgments 27 References 27 2 Mössbauer Spectral Studies of Iron Phosphate Containing Minerals and Compounds 33 Gary J. Long and Fernande Grandjean 2.1 Introduction 33 2.2 Thermodynamic Properties of Iron Phosphate Containing Compounds 34 2.3 Room Temperature Mössbauer Spectra of Iron Phosphate Containing Minerals 37 2.4 Analysis of Magnetically Ordered Mössbauer Spectra 50 2.5 Structural and Thermodynamic Properties of the Polymorphs of FePO4 53 2.5.1 Polymorphs of FePO4 53 2.6 Mössbauer Spectra of α-FePO4 55 2.7 Magnetic Structure of α-FePO4 , Obtained by Mössbauer Spectroscopy 57 2.7.1 Magnetic Structure of α-FePO4 57 2.8 Temperature Dependence of the α-FePO4 Structure Tilt Angle 60 2.9 Mössbauer Spectral Studies on Metastable Polymorphs of FePO4 62 2.9.1 Crystallographic Structures of Two Polymorphs of FePO4 ⋅2H2 O 62 2.9.2 Preparation and Crystallographic Structures of the Two Polymorphs, γ-FePO4 and ζ-FePO4 62 2.9.3 Mössbauer Spectral Studies of FePO4 Metastable Polymorphs 64 2.9.4 Preparation and Mössbauer Spectra of Synthetic Heterosite, (Fe,Mn)PO4 67 2.9.5 Fits of the Magnetic Mössbauer Spectra of η-Fe 0.9 Mn 0.1 PO4 68 2.10 Mössbauer Spectral Studies of Various Iron Phosphate Compounds 73 2.10.1 Mössbauer Spectral Properties of α-Fe2 (PO4)O 74 2.10.2 Mössbauer Spectral Properties of Fe3 (PO4)O3 79 2.10.3 Preparation and Structural Properties of Fe9 (PO4)O8 80 2.10.4 Mössbauer Spectral Properties of Fe9 (PO4)O8 81 Acknowledgments 85 References and Notes 85 3 Mössbauer Spectroscopic Investigation of Fe-Based Silicides 93 Xiao Chen, Junhu Wang, and Changhai Liang 3.1 Introduction 93 3.2 Mössbauer Spectroscopic Investigation of Iron Silicides Prepared By Mechanical Alloying and Heat Treatment 95 3.3 Mössbauer Spectra of Iron Silicide on Silica Prepared by Pyrolysis of Ferrocene-Polydimethylsilane Composites 99 3.4 Synthesis and Mössbauer Spectra of Iron Silicides by Temperature-Programmed Silicification 102 3.5 Mössbauer Spectroscopic Investigation of Doped Iron Silicides 104 3.6 Conclusion and Perspective 107 References 108 4 Mössbauer Spectroscopy of Catalysts 113 Károly Lázár 4.1 Introduction 113 4.2 Principles of the Mössbauer Effect and Outlook of Its Application for Catalyst Studies 116 4.2.1 Brief Overview of the Basics of Mössbauer Spectroscopy 116 4.2.2 Mössbauer Spectroscopy from the Point of View of Catalyst Studies – Particular Features 117 4.2.3 The Probability of the Mössbauer Effect – f-Factor and Size Effects 118 4.2.4 Variants of the Technique 120 4.2.4.1 57Co Emission Spectroscopy 120 4.2.4.2 Synchrotron-Based NFS (Nuclear Forward Scattering) 122 4.2.4.3 Conversion Electron Mössbauer Spectroscopy 122 4.2.5 Technical Implementations – Experimental Conditions 123 4.3 Heterogeneous Catalysts 124 4.3.1 Sites on Supported Particles with Different Participation in Catalytic Processes 124 4.3.2 Collective Effects in Particles (Magnetism) 125 4.3.3 Case Studies 126 4.3.3.1 Metals and Alloys 126 4.3.3.2 Oxide Catalysts 130 4.3.3.3 Catalysts with Fe–N, Fe–C, and Fe–N–C Centers 133 4.4 Biocatalysts – Enzymes 135 4.5 Homogeneous Catalysts – Frozen Solutions 135 4.5.1 Studies on Reaction Intermediates – Time-Resolved Freeze-Quenched Spectra 136 4.6 Conclusions 137 Acknowledgment 137 References 138 5 Application of Mössbauer Spectroscopy in Studying Catalysts for CO Oxidation and Preferential Oxidation of CO in H2 145 Kuo Liu, Junhu Wang, and Tao Zhang 5.1 Introduction 145 5.2 Application of Mössbauer Spectroscopy in CO Oxidation 147 5.2.1 57 Fe Mössbauer Spectroscopy 147 5.2.2 119 Sn Mössbauer Spectroscopy 150 5.2.3 197 Au Mössbauer Spectroscopy 151 5.2.4 193 Ir Mössbauer spectroscopy 152 5.3 Application of Mössbauer Spectroscopy in PROX 153 5.3.1 PtFe-Containing Catalysts 153 5.3.2 Au-Based Catalysts 155 5.3.3 IrFe-Containing Catalysts 158 5.3.3.1 Porous Carbon Supported IrFe Catalysts 158 5.3.3.2 SiO2 and Al2 O3 Supported IrFe Catalysts 159 5.3.4 CuO/CeO2 with Fe2 O3 Additive 165 5.4 Concluding Remarks 165 Acknowledgments 166 References 166 6 Application of 57 Fe Mössbauer Spectroscopy in Studying Fe–N–C Catalysts for Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cells 171 Xinlong Xu, Junhu Wang, Suli Wang, and Gongquan Sun 6.1 Introduction 171 6.2 Advanced 57Fe Mössbauer Spectroscopy Technique 173 6.2.1 Room Temperature 57Fe Mössbauer Spectroscopy 173 6.2.2 Low Temperature and Computational 57Fe Mössbauer Spectroscopy 174 6.2.3 In Situ Electrochemical 57Fe Mössbauer Spectroscopy 175 6.3 Characterization of Fe–N–C Using 57Fe Mössbauer Spectroscopy 177 6.3.1 Identification of Active Sites 177 6.3.2 Investigation of Degradation Mechanism 180 6.3.3 Optimization for Synthesis of Fe–N–C 184 6.3.3.1 Precursor Composition 184 6.3.3.2 Heat Treatment 185 6.4 Summary and Perspective 187 Acknowledgments 188 References 188 7 197 Au Mössbauer Spectroscopy of Thiolate-protected Gold Clusters 195 Norimichi Kojima, Yasuhiro Kobaqyashi, and Makoto Seto 7.1 Introduction 195 7.2 Synthesis of Thiolate Protected Gold Clusters 197 7.3 197 Au Mössbauer Spectroscopy of Gold Nano-clusters 198 7.3.1 Experimental Procedure of 197 Au Mössbauer Spectroscopy 198 7.3.2 197 Au Mössbauer Spectra of Aun (SG)m(n = 10∼55) 198 7.3.3 Molecular Structure and 197 Au Mössbauer Spectra of Au10 (SG)10 198 7.3.4 Molecular Structure and 197 Au Mössbauer Spectra of Au25 (SG)18 200 7.3.5 Structural Evolution of Aun (SG)m(n = 10∼55) Based on 197 Au Mössbauer Spectroscopy 201 7.3.6 197 Au Mössbauer Spectra of Au24 Pd1 (SC12 H25)18 204 7.3.7 197 Au Mössbauer Spectra of Aun (SC12 H25)m 205 7.4 Conclusion 208 Acknowledgments 208 References 209 8 197 Au Mössbauer Spectroscopy of Gold Mixed-Valence Complexes, Cs2 [AuI X2 ][AuIII Y4 ](X, Y = Cl, Br, I) and [NH3 (CH2)n NH3 ]2[(AuI I2)(AuIII I4)(I3)2](n= 7, 8) 213 Norimichi Kojima, Yasuhiro Kobaqyashi, and Makoto Seto 8.1 Introduction 213 8.2 Experimental Procedure 216 8.2.1 Synthesis and Characterization 216 8.2.1.1 Cs2 [AuI X2][AuIII Y4 ](X,Y= Cl, Br, I) 216 8.2.1.2 [NH3 (CH2)n NH3 ]2 [(AuI I2)(AuIII I4)(I3)2 ](n= 7, 8) 217 8.2.2 197 Au Mössbauer Spectroscopy 217 8.3 Crystal Structure of Cs2 [AuI X2][ AuIII X4](X,Y= Cl, Br, I) 218 8.4 Chemical Bond of Au−Xin[AuI X2] − and [AuIII X4] − 221 8.5 Mössbauer Parameters of 197 Au in [AuI X2] − and [AuIII X4 ] − 223 8.5.1 Mössbauer Parameters of 197 Au in (C4 H9)4 N[AuI X2] and (C4 H9)4 N[AuIII Y4] 224 8.5.1.1 Isomer Shift 224 8.5.1.2 Quadrupole Splitting 224 8.5.2 Mössbauer Parameters of 197 Au in Cs2 [AuI X2] [ AuIII Y4] (X = Cl, Br, I) 225 8.5.2.1 Isomer Shift 225 8.5.2.2 Quadrupole Splitting 226 8.5.2.3 Analysis of 197 Au Mössbauer Parameters for Cs2 [AuI X2] [ AuIII Y4] 226 8.6 Charge Transfer Interaction in Cs2 [AuI X2] [ AuIII Y4](X= Cl, Br, I) 227 8.7 197 Au Mössbauer Spectra of Cs2 [AuI X2] [ AuIII Y4](X,Y= Cl, Br, I) 228 8.7.1 Isomer Shift of AuI in Cs2 [AuI X2] [ AuIII Y4] 228 8.7.2 Isomer Shift of AuIII in Cs2 [AuI X2] [ AuIII Y4] 230 8.7.3 Quadrupole Splitting of AuI in Cs2 [AuI X2 ] [AuIII Y4 ] 230 8.7.4 Quadrupole Splitting of AuIII in Cs2 [AuI X2] [AuIII Y4 ] 231 8.8 Single Crystal 197 Au Mössbauer Spectra of Cs2 [AuI I2 ] [AuIII I4 ] 231 8.8.1 Comparison of 197 Au Mössbauer Spectra Between Single Crystal and Powder Crystal 231 8.8.2 Sign of EFG for AuI in [AuI I2 ] − and AuIII in [AuIII X4 ] − 234 8.9 197 Au Mössbauer Spectra of Cs2 [AuI X 2 ] [AuIII X4 ](X= Cl, I) Under High Pressures 235 8.9.1 Phase Diagram of Cs2 [AuI X2 ] [AuIII X4 ](X= Cl, Br, I) 235 8.9.2 Origin of Metallic Mixed-Valence State in Cs2 [AuI Cl2 ] [AuIII Cl4 ] 236 8.9.3 Au Valence Transition in Cs2 [Au II2 ] [AuIII I4 ] 239 8.10 197 Au Mössbauer Spectra of [NH3 (CH2)n NH3 ]2 [(Au II2)(AuIII I4)(I3)2 ] (n = 7, 8) 241 8.11 Conclusion 243 Acknowledgments 244   References 245 9 Temperature- and Photo-Induced Spin-Crossover in Molecule-Based Magnets 251 Hiroko Tokoro, Kenta Imoto, and Shin-ichi Ohkoshi 9.1 Introduction 251 9.2 Spin-Crossover Phenomena in Cesium Iron Hexacyanidochromate Prussian Blue Analog 252 9.3 Light-Induced Spin-Crossover Magnet in Iron Octacyanidoniobate Bimetal Assembly 254 9.4 Chiral Photomagnetism and Light-Controllable Second Harmonic Light in Iron Octacyanidoniobate Bimetal Assembly 258 9.5 Conclusion and Perspective 265 References 265 10 Developing a Methodology to Obtain New Photoswitchable Fe(II) Spin Crossover Complexes 271 Varun Kumar and Yann Garcia 10.1 Introduction and Context 271 10.2 Introduction to a New Photo-responsive Anion: psca 275 10.3 Combining Fe(II) and psca Together in a Single Compound 276 10.4 Fe(II) Mononuclear Complexes with DMPP and psca Ligands 278 10.5 1D Fe(II) Coordination Polymer with psca as Non-Coordinated Anions 281 10.6 Conclusions and Perspectives 284 References 285 11 57 Fe Mössbauer Spectroscopy as a Prime Tool to Explore a New Family of Colorimetric Sensors 291 li Sun, Weiyang li, and Yann Garcia 11.1 Introduction and General Context 291 11.2 Colorimetric Gas Sensors Based on Fe(II) Complexes 292 11.3 Conclusions and Perspectives 306 References 306 Index 311

Unique and comprehensive overview of versatile applications of Mössbauer spectroscopy in chemistry and material sciences Mössbauer Spectroscopy provides a comprehensive overview of relevant applications of this physical analysis method in chemistry and material sciences. The book shows the versatility of Mössbauer spectroscopy in finding useful information on electronic structure, structural insights, and solid-state effects of chemical systems. A wide range of chemical applications and applied concepts are covered as well as numerous examples, selected from recent literature. To aid in reader comprehension and accessibility, contents are well-structured and divided in different sections covering energy, catalysis, coordination chemistry, spin crossover, sensing, photomagnetism. Edited by prominent scientists in the field and authored by a group of international experts, Mössbauer Spectroscopy covers sample topics such as: Li-ion batteries, catalysts, fuel cells, Fe based silicides and iron phosphates containing mineralsGold clusters and gold mixed valence complexesMolecule based magnets, photoswitchable spin crossover coordination polymers and molecular sensors for meat freshness control With comprehensive coverage of the developments in the technique, Mössbauer Spectroscopy is a beneficial resource for researchers, professionals, and academics in chemistry related fields, such as material science, sustainable environment, and molecular electronics. It can be used by newcomers as well as for educational purposes at the master and PhD levels.