Silver-based nanoparticles Synthesis and characterization of bimetallic silver- platinum and silver-gold nanoparticles Dissertation Zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften Dr. rer. nat. vorgelegt von Viktoria Grasmik Fakultät für Chemie Institut für Anorganische Chemie Universität Duisburg-Essen 2018 II Die vorliegende Arbeit wurde im Zeitraum von April 2015 bis Mai 2018 im Arbeitskreis von Prof. Dr. Matthias Epple am Institut der Anorganischen Chemie der Universität Duisburg-Essen angefertigt. Gutachter: Prof. Dr. Matthias Epple Prof. Dr. Malte Behrens Vorsitzender: PD Dr. Holger Somnitz Tag der Disputation: 04.09.2018 III IV List of contents List of contents Index of abbreviations ................................................................................... VIII Abstract ............................................................................................................... X Deutscher Abstract ............................................................................................ XI 1. Introduction ..................................................................................................... 1 2. Theoretical background .................................................................................. 4 2.1 Colloids, nanoclusters, and nanoparticles – a definition .................................................. 4 2.2 Stabilization of nanoparticles ............................................................................................ 5 2.3 Synthesis routes and crystallization processes .................................................................. 8 2.4 Optical properties of metallic nanoparticles ................................................................... 11 2.5 Employed metals and their properties ............................................................................ 13 2.5.1 The binary silver-gold system .................................................................................. 16 2.5.2 The binary silver-platinum system ........................................................................... 18 3. Methods .......................................................................................................... 20 3.1 Dynamic Light Scattering and Zeta Potential ................................................................. 20 3.2 Differential Centrifugal Sedimentation .......................................................................... 20 3.3 UV/vis spectroscopy ....................................................................................................... 21 3.4 Fluorescence spectroscopy.............................................................................................. 22 3.5 Atomic Absorption Spectrometry ................................................................................... 22 3.6 Energy Dispersive X-ray Spectroscopy .......................................................................... 23 3.7 Scanning Electron Microscopy ....................................................................................... 23 3.8 Transmission Electron Microscopy ................................................................................ 24 3.9 Powder X-ray Diffraction ............................................................................................... 24 3.10 Electrochemistry – Cyclic Voltammetry and Underpotential Deposition .................... 26 4. Experimental .................................................................................................. 27 4.1 Programs/databases used ................................................................................................ 27 V List of contents 4.2 Chemicals used ............................................................................................................... 28 4.3 Devices used ................................................................................................................... 29 4.4 Synthesis of silver-platinum nanoparticles..................................................................... 30 4.4.1 Reduction by trisodium citrate and tannic acid ....................................................... 30 4.4.2 Reduction by sodium borohydride at pH 3 .............................................................. 32 4.4.3 Reduction by sodium borohydride at pH 10 ............................................................ 32 4.5 Synthesis of silver-platinum nanoclusters ...................................................................... 33 4.6 Synthesis of silver-gold nanoparticles ............................................................................ 33 4.6.1 Reduction by trisodium citrate and tannic acid ....................................................... 34 4.6.2 Reduction by trisodium citrate ................................................................................. 35 4.7 Dissolution experiments ................................................................................................. 36 4.7.1 Dissolution of silver-gold nanoparticles .................................................................. 36 4.7.2 Dissolution of silver-platinum nanoparticles ........................................................... 36 4.8 Synthesis of monometallic nanoclusters and nanoparticles ........................................... 37 4.8.1 Synthesis of autofluorescent palladium nanoclusters .............................................. 37 4.8.2 Synthesis of silver nanoparticles and ligand exchange from trisodium citrate to poly(ethylene glycol) methyl ether thiol ................................................................. 38 5. Results and discussion ................................................................................... 39 5.1 Characterization of silver-platinum nanoparticles ......................................................... 39 5.1.1 Synthesis by trisodium citrate and tannic acid reduction ........................................ 39 5.1.2 Synthesis by sodium borohydride reduction at pH 3 ............................................... 46 5.1.3 Synthesis by sodium borohydride reduction at pH 10 ............................................. 67 5.1.4 Conclusion on silver-platinum nanoparticles .......................................................... 74 5.2 Characterization of silver-platinum nanoclusters ........................................................... 75 5.2.1 Conclusion on silver-platinum nanoclusters ............................................................ 82 5.3 Characterization of silver-gold nanoparticles................................................................. 83 5.3.1 Synthesis by trisodium citrate and tannic acid reduction ........................................ 83 5.3.2 Synthesis by trisodium citrate reduction ................................................................ 116 VI List of contents 5.3.3 Conclusion on silver-gold nanoparticles ................................................................ 132 5.4 Evaluation of dissolution experiments .......................................................................... 133 5.4.1 Dissolution of silver-gold nanoparticles ................................................................ 133 5.4.2 Dissolution evaluation of silver-platinum nanoparticles ........................................ 139 5.4.3 Conclusion on the dissolution experiments ............................................................ 142 5.5 Characterization of monometallic nanoclusters and nanoparticles ............................... 143 5.5.1 Characterization of autofluorescent palladium nanoclusters ................................. 143 5.5.2 Characterization of silver nanoparticles after refunctionalization with poly(ethylene glycol) methyl ether thiol ................................................................ 145 5.5.3 Conclusion on the monometallic nanoclusters and nanoparticles .......................... 147 6. Conclusion .................................................................................................... 148 7. References .................................................................................................... 150 8. Appendix ...................................................................................................... 161 8.1 High-temperature X-ray diffraction .............................................................................. 161 8.2 Dissolution experiments ............................................................................................... 165 8.2.1 Silver-gold nanoparticles........................................................................................ 165 8.2.2 Silver-platinum nanoparticles ................................................................................ 169 8.3 List of publications ....................................................................................................... 171 8.4 Posters and presentations .............................................................................................. 172 8.5 Curriculum Vitae .......................................................................................................... 173 8.6 Acknowledgements ....................................................................................................... 174 8.7 Eidesstaatliche Erklärung.............................................................................................. 175 VII Index of abbreviations Index of abbreviations Abbreviation Meaning AAS Atomic absorption