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Plasma electrochemical reduction for nanomaterials synthesis and assembly

Lee, Seung Whan
http://rave.ohiolink.edu/etdc/view?acc_num=case1333653828

Abstract Details

2012, Doctor of Philosophy, Case Western Reserve University, Biomedical Engineering.
The recent development of microscale plasmas allows the formation of ions, electrons, and other energetic species near ambient conditions (i.e. room temperature and atmospheric pressure). As a source of charged species, microplasmas are suitable for novel electrochemical applications, for example to initiate electrochemical reactions through the reaction of gas-phase electrons with ionic solutions or ionic films. In this dissertation, we demonstrate several examples of plasma electrochemistry with the purpose of synthesizing and assembling metal nanoparrticles. To better understand and study the role of gas-phase electrons in plasma electrochemistry, we initially study a model reaction in solution, the reduction of ferricyanide to ferrocyanide. Our experiments show that a microplasma can indeed reduce ferricyanide, confirming that a plasma discharge can serve as a source of electrons for electrochemical reactions in solution. These studies then lead to the main focus of the dissertation which is reduction of metal ions dispersed on surfaces to fabricate patterns of nanomaterials. Towards this end, we present three general approaches to nanofabrication based on plasma electrochemistry 1) direct writing of metal nanoparticles, 2) lithographic pattern transfer of metallic materials at the nanoscale, and 3) directed assembly of metal nanoparticles via metallopolymer-based molecular templates. Direct writing of metal nanoparticles is achieved by exposing spin-coated films of metal salts and polymer to a rastered microplasma. As the films are exposed to the plasma, the metal ions are reduced and nanoparticles are nucleated. Thus, patterns of size close to the microplasma (~100 μm) are transferred to a film to produce a flexible, patterned film of metal nanoparticles. To reduce the pattern size, we have extracted a low-current discharge from the main microplasma discharge and incorporated a nanomask such as an alumina membrane template to transfer patterns by lithography. The extracted discharge allows electrons to interact with the patterned film without ion bombardment. Further reduction in the resolution of the transferred patterns is achieved by metallo-supramolecular polymer chemistry. These novel materials contain inorganic (metal) moieties and self assemble into films with macroscopic order. Reduction of the metal component by plasma electrons results in the formation of well-dispersed, nanometer-sized (<3 nm) metal nanoparticles with long-range order. Overall, these approaches to nanopartterning based on plasma electrochemistry are low cost and scalable and amenable to roll-to-roll processing which is attractive for emerging technological applications in catalysis, energy, and medicine.
R. Mohan Sanakaran (Committee Chair)
Chung-Chiun Liu (Committee Member)
Daniel J. Lacks (Committee Member)
Stuart J. Rowan (Committee Member)
129 p.
Chemical Engineering
microplasma; plasma electrochemistry; nanomaterial; nanofabrication

Recommended Citations

Citations

  • Lee, S. W. (2012). Plasma electrochemical reduction for nanomaterials synthesis and assembly [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1333653828

    APA Style (7th edition)

  • Lee, Seung Whan. Plasma electrochemical reduction for nanomaterials synthesis and assembly. 2012. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1333653828.

    MLA Style (8th edition)

  • Lee, Seung Whan. "Plasma electrochemical reduction for nanomaterials synthesis and assembly." Doctoral dissertation, Case Western Reserve University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1333653828

    Chicago Manual of Style (17th edition)

case1333653828
619
© 2012, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.