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Use of bipolar electrochemistry in nanoscience: contact free methods for the site selective modification of nanostructured carbon materials (The)
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http://hdl.handle.net/1860/275
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| Title: | Use of bipolar electrochemistry in nanoscience: contact free methods for the site selective modification of nanostructured carbon materials (The) |
| Authors: | Ndungu, Patrick Gathura |
| Keywords: | Nanostructured materials
Electroplating
Electrochemistry |
| Issue Date: | 22-Mar-2004 |
| Abstract: | Bipolar electrochemistry occurs when an isolated conductive substrate inside an electric field supports both oxidation and reduction reactions. The method requires no direct contact between the power supply and the substrate. In the following thesis bipolar electrochemistry has been used to deposit palladium onto isolated graphite platelets, carbon nanofibers (CNF), and carbon nanotubes (CNT), as well as, various metals, a semiconductor, and an electropolymer on CNTs. Initial work used pulsed DC electric fields to deposit palladium onto isolated graphite platelets. Transmission electron
microscopy (TEM) studies on the platelets found palladium metal on one area, indicative of a bipolar mechanism, and palladium deposits that varied from surface bound to highly ramified deposits. No correlation was found between
the frequency used to prepare the deposits and the palladium metal dispersion. The same field intensities and frequencies used on the graphite
platelets were used to produce CNFs with palladium on one tip. The amount of palladium deposited on one tip of a CNF was controlled by adjusting how long the electric field was applied. Preliminary experiments to produce bulk
quantities of CNFs with palladium bipolar electrodeposits used CNFs ball milled with silica, and CNFs suspended in tetrahydrofuran or methylene chloride. The palladium content, measured by atomic absorption spectroscopy,
of the functionalized CNFs in silica showed no difference with increased CNF loading; however, TEM studies found a small number of functionalized CNFs with palladium on one tip. Work on CNFs suspended in THF and methylene
chloride used suspensions with high loadings of CNFs which led to small percentages of CNFs with bipolar electrodeposited palladium. Finally CNTs
obtained commercially and CNTs grown using chemical vapor deposition were successfully functionalized using bipolar electrodeposition. These experiments demonstrate a reliable and controlled method to modify nanostructured materials. |
| URI: | http://dspace.library.drexel.edu/handle/1860/275 |
| Appears in Collections: | Drexel Theses and Dissertations
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