Understanding factors that control interfacial electron transfer (ET) kinetics is a key to solving problems in many fields ranging from corrosion protection, lithium batteries, to organic electronic devices. Over the past few decades, interfacial ET kinetics was one of the fields in electrochemistry to have been extensively studied in the context of diverse processes including ET process across complex solid-electrolyte interface (SEI) layers in lithium batteries as well as ET process at simple chemically-modified electrodes (CME). Studies of the latter case have been mainly focused on CME containing electrochemically active species with various alkyl chains in between electrode surface and electrochemically active species, concluding that such ET kinetics is controlled by the distance between electrochemically active species and electrode surface, i.e. the length of the alkyl chains. While, it is almost obvious to conclude that long alkyl chains at the electrode surface act as an insulating layer for the ET processes, the mechanism of ET process between shorter alkyl chain modified electrode surface and electrochemically active species in solution is still unclear. Further investigation towards understanding the role of solvation involved in the ET process is required. Herein, we report electrochemical behaviors of both perfluoroalkyl and alkyl modified glassy carbon (GC) electrodes with relatively short alkyl and fluoroalkyl chains. We find that heterogeneous ET kinetic rates of ferrocenium/ferrocene (Fc+/Fc) redox couple in 1,2-difluorobenzene solution were only reduced slightly with ΔEp increasing less than 10 mV (from ~69 mV to ~79 mV) at 100 mV/s potential sweep rate. However, significantly slower ET rates were observed for ferricyanide/ferrocyanide (Fe(CN)63-/4-) redox couple in aqueous solution with ΔEp increasing up to 360 mV (from ~70 mV to ~430 mV). These results indicate that the interfacial solvation significantly affects the heterogeneous ET kinetics at perfluoroalkyl and alkyl modified electrodes. Possible solvation models and reorganization processes associated with the interfacial ET processes will be discussed during the presentation.

Perfluoroalkyl and alkyl modified glassy carbon electrodes: A model system to understand role of solvation in interfacial electron transfer kinetics

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.