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X-ray Structural Studies of Electroactive Films

By Magdalena Anna Skopek

Abstract

This thesis describes X-ray studies (XANES, EXAFS and XAS) of the structures of electroactive film modified electrodes and their response to potential. To provide insight into the composition, structure and dynamics of the studied systems EXAFS was combined with other techniques: XPS, electrochemical methods and infrared spectroscopy. The electroactive materials studied were Prussian Blue (PB) and its cobalt and nickel derivatives, iridium oxide and polypyrrole/[P(Mo3O10)4]3- composite films.\ud Selected electroactive materials were diverse, since the study was undertaken with the aim of providing the foundations for future experiments in the area of the dynamic in situ EXAFS research.\ud For cobalt hexacyanoferrate films, cobalt was identified as the active redox site, based on clear evidence of changing bond lengths with potential. This suggests it will be an interesting candidate for future dynamic EXAFS study. The behaviour of PB films was found to be complicated to interpret because both redox sites are Fe-based and there exist additional interstitial iron species. In contrast to cobalt hexacyanoferrate, no significant changes could be observed in the Ni XAS data for the nickel derivative with Fe active redox sites. Polypyrrole/[P(Mo3O10)4]3- composite films showed changes in oxidation state of multiple Mo sites in XPS experiments. Nevertheless, they are not a promising material for a dynamic EXAFS because of the interpretational problems, similar to PB films. Iridium oxide films are another promising candidate. They were successfully characterized in in situ EXAFS configuration and changing bond lengths were observed as the potential (and thus Ir oxidation state) was changed.\ud Additionally the thesis includes nanogravimetric observation of ion exchange characteristics of polypyrrole film p-doping in an ionic liquid. It is shown that polypyrrole film redox switching in the deep eutectic ionic liquid (Ethaline) involves a very different pattern of ion transfers to aqueous media. Ionic liquid in the reduced film provides a reservoir of choline cations whose transfer (in the opposite direction to anion doping) partly satisfies electroneutrality.\ud Overall, the sites of redox activity were identified in a range of multi-site redox systems and structural changes were related to the injected charge. This static study is the first step in identifying systems suitable for X-ray synchrotron-based dynamic studies of electroactive film structure

Publisher: University of Leicester
Year: 2010
OAI identifier: oai:lra.le.ac.uk:2381/8644

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Citations

  1. (1987). A doi
  2. (2001). A all-plastic WO3 x H2O/polyaniline electrochromic device. doi
  3. (2002). Acta doi
  4. (1995). An Introduction to EXAFS Data Analysis.
  5. (1995). B., in Applications of Electroactive Polymers, doi
  6. (2008). Conducting Polymers in Electrodeposition from Ionic Liquids. Eds.: doi
  7. (1999). Conducting Polymers, Fundamentals and Applications. A Practical Approach. doi
  8. (1993). Determining Atomic Structure at Electrode/Electrolyte Interfaces.
  9. (1980). Elecrochemical Methods. Fundamentals and Applications.
  10. (2006). Electrochemical Methods. Fundamentals and Applications. doi
  11. (1995). Electrochemical Quartz Crystal Microbalance Studies of Electroactive Surface Films. doi
  12. (2007). Electrochromism by intervalence charge-transfer coloration: metal hexacyanometallates in Electrochromism and Electrochromic Devices. doi
  13. (1996). Electrode Dynamics.
  14. (2008). Electrodeposition from Ionic Liquids. doi
  15. (2006). Extended X-ray Absorption Fine Structure in Neutron and X-ray Spectroscopy. Eds.: F. Hippert et al; doi
  16. (2007). Fibers and Polymers doi
  17. (2006). First year report.
  18. (2004). Fundamentals of XAFS. In doi
  19. (1998). Handbook of Conducting Polymers.
  20. (2007). Handbook of Electrochemistry, Elsevier: doi
  21. (1992). Handbook of X-ray Photoelectron Spectroscopy.
  22. (1992). Handbook of X-ray Photoelectron Spectroscopy. Perkin-Elmer Corporation,
  23. (1983). Heteropoly and Isopoly Oxometalates. doi
  24. (1993). Interface doi
  25. (2006). Interface Anal. doi
  26. (2006). L'actualite chimique
  27. (2004). Magnetic Prussian Blue Analogs in Magnetism: Molecules to materials, doi
  28. (2008). Nanogravimetric observation of unexpected ion exchange characteristics for polypyrrole film p-doping in a deep eutectic ionic liquid, doi
  29. (1965). Physics of Non-crystalline Solids.
  30. (2000). Power Sources doi
  31. (1959). Quantum Mechanics of One- and Two-electron Systems. doi
  32. (2007). Solid State Electr. doi
  33. (2007). Solid State Electrochem. doi
  34. (2003). Solid State Ionics doi
  35. (2001). Sources doi
  36. State Chemistry and its Applications. doi
  37. (1990). Synchrotron Radiation and Biophysics. Ellis Horwood:
  38. (2007). Thesis, Gravimetric and Viscoelastic Investigations of Electroactive Films.
  39. (2001). Thesis, Structural Studies of Electroactive Transition Metal Oxide Films.
  40. (2001). Thesis, Structural Studies of Electroactive Transition Metal Oxide Films. Thesis,
  41. (1999). Thin Solid Films doi
  42. (1970). X-ray Anal. doi

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