Polyviologen-modified anodes for carbohydrate biofuel cells

Wang, Pingmei

Polyviologen-modified anodes for carbohydrate biofuel cells

dc.contributor.advisor	Glatzhofer, Daniel
dc.contributor.author	Wang, Pingmei
dc.contributor.committeeMember	Crossley, Steven
dc.contributor.committeeMember	Shao, Yihan
dc.contributor.committeeMember	Yip, Wai Tak
dc.date.accessioned	2021-04-06T15:41:19Z
dc.date.available	2021-04-06T15:41:19Z
dc.date.issued	2021-05-14
dc.date.manuscript	2021-03-30
dc.description.abstract	Polyalkylviologens (PVCn (n = 2 - 6)) were successfully deposited on glassy carbon electrodes (GCEs) by electropolymerization of bis(4-cyano-1-pyridino)-alkane dibromides (PyCnBr2 (n = 2 - 6)) as precursors. By studying the adsorption behavior of methyl, ethyl and propyl viologen in aqueous solutions, the polymerization pathway to form PVCn (n = 2 and 3) is proposed to be reduction, coupling, eliminative viologen formation, and deposition, while PVCn (n = 4, 5, and 6) are formed by reductive adsorption, coupling, and eliminative polyviologen formation. The electrochemical behaviours of PVC5 and PVC6 suggest they have relatively open, flexible structures. PyC5Br2 was crosslinked by electrocopolymerization with 1,3,5-tris(4- cyanopyridinio-1-methyl)-2,4,6-trimethylbenzene tribromide (PyBenMeBr3) to form viologen copolymers. The copolymer compositions were changed by using different concentrations of PyC5Br2 and PyBenMeBr3 in the electropolymerization mixtures. Compared with no current response of PVC5 after 50 successive scan cycles in pH 12 solution, the copolymer retained electrochemical activity. The copolymer, deposited onto three-dimensional carbon nanotube-modified GCE anodes, produced current densities up to 121.6 uA/cm2 in fuel cells with a Pt/Nafion film cathode and in 5 mM glucose 0.1 M KCl solution at pH 9.7. On carbon felt anodes, the copolymer produced currents up to 587.9 uA and powers up to 90.6 uW. Lowering the fuel cell solution to pH 8.1, the maximum current generated by the copolymer on carbon felt anodes decreased to 445.6 uA. PyCnBr2 (n = 4, 5, and 6) was encapsulated by cucurbit[7]uril (CB[7]) to form PyCnBr2@CB[7] pseudorotaxanes. PyCnBr2@CB[7] were successfully polymerized to PVCn@CB[7]. PVCn@CB[7] showed slightly more negative redox potential shifts than PVCn. PVC5@CB[7]'s electrochemical activity is extremely stable in pH 12 aqueous solution. PVC5@CB[7]-modified carbon felt anodes produced maximum currents of 585 uA and powers of 122 uW in a glucose fuel cell with a Pt/Nafion film cathode and in 5 mM glucose 0.1 M KCl solution at pH 9.7.	en_US
dc.identifier.uri	https://hdl.handle.net/11244/329091
dc.subject	Biofuel cells	en_US
dc.subject	Polyviologen	en_US
dc.subject	Electrosynthesis	en_US
dc.thesis.degree	Ph.D.	en_US
dc.title	Polyviologen-modified anodes for carbohydrate biofuel cells	en_US
ou.group	College of Arts and Sciences::Department of Chemistry and Biochemistry	en_US