SYNTHESIS AND APPLICATIONS OF SILVER AND PALLADIUM NANO METAL FOAMS _______________________________________ A Thesis presented to the Faculty of the Graduate School at the University of Missouri-Columbia _______________________________________________________ In Partial Fulfillment of the Requirements for the Degree Master of Science _____________________________________________________ by SIJIA HU Dr. Sheila N. Baker, Thesis Supervisor DEC 2013 The undersigned, appointed by the dean of the Graduate School, have examined the thesis entitled SYNTHESIS AND APPLICATIONS OF SILVER AND PALLADIUM METAL NANO FOAMS Presented by Sijia Hu, a candidate for the degree of master of Science, and hereby certify that, in their opinion, it is worthy of acceptance. Professor Sheila N. Baker Professor David Retzloff Professor John M. Gahl DEDICATION This thesis is dedicated to my amazing parents, cousins, and friends that have helped and supported me all the way since the beginning of my research. I could not have done it without you. Also, this thesis is dedicated to all those who believe in the richness of learning. ACKNOWLEDGEMENTS First and foremost, I would like to express my sincere gratitude to Dr. Sheila N. Baker for the valuable guidance and advice. She inspired me greatly to work in my research. Her willingness to motivate me contributed tremendously to my research project in the past two years. I would also like to thank Dr. David Retzloff and Dr. John M. Gahl for their willingness to be members of my thesis committee and for offering me with a good environment, facilities and kind help to complete this research project. Also, I wish to thank Zhifeng Lu who has been supporting me with helpful suggestions and assurance throughout the whole research project. In addition, I wish to thank all the members of Dr. Sheila N. Baker’s research group for their help and encouragement. Finally, an honorable mention goes to my family and friends for their understandings and supports on us in completing this project. ii TABLE OF CONTENTS ACKNOWLEDGEMENTS ......................................................................................ii TABLE OF CONTENTS ....................................................................................... iii TABLE OF FIGURES ........................................................................................... v LIST OF ABBREVIATIONS ..................................................................................ix ABSTRACT .......................................................................................................... x CHAPTER 1: INTRODUCTION ............................................................................ 1 1.1 Definition of Nanoporous Metal Foams ................................................... 1 1.2 Synthetic Methods for NMFs ................................................................... 3 1.3 Applications of NMFs............................................................................... 5 1.3.1 Surface-Enhanced Raman Spectroscopy (SERS) ............................... 5 1.3.2 Viable hydrogen storage ....................................................................... 7 1.3.3 Electrochemical actuators .................................................................... 7 1.3.4 Green Chemistry .................................................................................. 8 1.3.5 High Power Density Batteries ............................................................... 9 1.4 Instruments ............................................................................................ 10 1.4.1 Microwave .......................................................................................... 10 1.4.2 Scanning Electron Microscope ........................................................... 12 1.4.3 Brunauer-Emmett-Teller (BET) Analysis ............................................ 14 1.4.4 Raman Spectroscope ......................................................................... 16 1.4.5 Microplate Spectrophotometer ........................................................... 18 1.5 Motivation and Objective for Research .................................................. 20 CHAPTER 2: EXPERIMENTAL PROCEDURES AND MATERIALS .................. 23 2.1 Polyol Synthesis ........................................................................................ 23 iii 2.1.1 Materials ............................................................................................. 23 2.1.2 Polyol Synthesis Process ................................................................... 23 2.2 Hydrazine Synthesis ................................................................................. 25 2.2.1 Materials ............................................................................................. 25 2.2.2 Hydrazine Synthesis Process ............................................................. 25 2.2.3 Results and Discussions .................................................................... 27 2.2.4 Possible Mechanism........................................................................... 34 2.3 Sodium Borohydride Synthesis ................................................................. 36 2.3.1 Materials ............................................................................................. 36 2.3.2 Sodium borohydride synthesis process .............................................. 36 2.3.3 Results and Discussions .................................................................... 38 2.2.4 Possible Mechanism........................................................................... 44 CHAPTER 3: APPLICATION FOR SILVER ....................................................... 45 3.1 Silver NMFs applied in SERS ................................................................... 45 3.2 Experimental Section ................................................................................ 47 CHAPTER 4: APPLICATION FOR PALLADIUM ................................................ 52 4.1 Palladium NMFs applied in MO decoloration ............................................ 52 4.2 Experimental Section ................................................................................ 53 CHAPTER 5: Future Work and Conclusion ........................................................ 63 5.1 Future work ............................................................................................... 63 5.2 Conclusion ................................................................................................ 64 Reference ........................................................................................................... 67 iv TABLE OF FIGURES Figure 1.1 SEM image of Ni nanofaom produced by combustion synthesis. (Scale bar is 200nm). (Luther, Tappan et al. 2009) ....................................... 2 Figure 1.2 The SEM micrograph of the surface of nanoporous Pt sample.(Weissmuller 2003) ........................................................................... 8 Figure 1.3 Image of CEM microwave used for the synthesis of all NMFs, metal ions including gold, silver, palladium and nickel. ......................................... 11 Figure 1.4 Image of Hitachi S–4700 cold field emission SEM. (UniversityofMissouri-Columbia 1997) ......................................................... 13 Figure 1.5 Principle of SEM electron source ...................................................... 14 Figure 1.6 Image of the B&W TEK i-Raman ....................................................... 18 Figure 1.7 Image of BioTek Powerwave HT Microplate Spectrophotometer, used for the detection of decoloration of MO solution with palladium NMFs. ....... 19 Figure 2.1 Height adjustment of Hitachi S–4700 SEM specimen ....................... 27 Figure 2.2 SEM image of silver NMFs with a magnification is 6k made by hydrazine in the condition of 5 min, 150 W microwave heating. .................. 29 Figure 2.3 SEM image of silver NMFs with a magnification 13.0k made by hydrazine in the condition of 5 min, 150 W microwave heating. .................. 30 Figure 2.4 SEM image of silver NMFs with a magnification 45.0k made by hydrazine in the condition of 5 min, 150 W microwave heating. .................. 30 Figure 2.5 SEM image of Pd NMFs with a magnification 8.03k made by hydrazine in the condition of 5 min, 150 °C microwave heating. ................. 31 Figure 2.6 SEM image of Pd NMFs with a magnification 13.0k made by hydrazine in the condition of 5 min, 150 °C microwave heating. ................. 32 Figure 2.7 SEM image of Pd NMFs with magnification of 100k made by hydrazine in the condition of 5 min, 150 °C heating. ................................... 32 Figure 2.8 Nitrogen adsorption and desorption isotherm of the silver NMFs using hydrazine synthesis method. The BET surface area is 22.3 m2/g. .............. 33 v Figure 2.9 Nitrogen adsorption and desorption isotherm of the palladium NMFs using hydrazine synthesis method. The BET surface area is 11.5 m2/g. ..... 33 Figure 2.10 SEM image of silver NMFs with magnification of 10k made by NaBH4 in the condition of 5 min, 150 W heating. ........................................ 39 Figure 2.11 SEM image of silver NMFs with magnification of 18k made by NaBH4 in the condition of 5 min, 150 W heating. ........................................ 39 Figure 2.12 SEM image of silver NMFs with magnification of 70.0k made by NaBH4 in the condition of 5 min, 150 W heating. ........................................ 40 Figure 2.13 SEM image of Pd NMFs with magnification