Date of Graduation
Eberly College of Arts and Sciences
Harry O. Finklea.
Proton Coupled Electron Transfer (PCET) reactions play a vital rote in a variety of biological and chemical processes. Prior work by E. Laviron developed the theory of proton coupled electron transfer kinetics based on a stepwise mechanism with the transfer coefficient for electron transfer remaining constant at all overpotentials. The present work explores the consequences of a potential-dependent transfer coefficient as applied to redox couples attached to electrodes. Specifically, this work focuses on the 1-electron, 1-proton (1e1H) system. Derivation of the potential-dependence of the transfer coefficient comes from the Marcus density-of-states model of heterogeneous electron transfer. Two 1e1H systems are examined. Galvinol is an organic redox couple that forms a stable free radical, galvinoxyl, and exhibits 1e1H behavior. The thermodynamics and kinetics of electron transfer for a galvinol-terminated alkanethiol, adsorbed to a gold electrode, are explored. Also discussed is the inorganic 1e1H redox couple, [Os(bpy)2(4-AMP)OH2] 2+, attached to an alkanethiol that is adsorbed to a gold electrode. Results show that both the galvinol and the osmium redox couples behave as predicted by the thermodynamic model. However, for both systems, experimental results deviate significantly from the kinetic model.
Haddox, Robert M., "Electron transfer kinetic studies of 1-electron, 1-proton redox couples attached to electrodes" (2002). Graduate Theses, Dissertations, and Problem Reports. 1703.