Electron transfer kinetics on mono- and multilayer graphene

Area of Science:

• Electrochemistry
• Materials Science
• Surface Science

Background:

• Graphene's electrochemical properties are crucial for energy applications.
• Understanding electron transfer kinetics is key to realizing graphene's potential.
• Comparison with graphite and other carbon materials is needed.

Purpose of the Study:

• To measure the electron transfer rate of graphene using three redox mediators.
• To investigate the effect of layer number and surface conditions on graphene's reactivity.
• To compare the electrochemical performance of graphene with graphite.

Main Methods:

• Voltammetric determination of electron transfer rates.
• Mechanical exfoliation of natural graphite to prepare graphene samples.
• Microscopic droplet technique to measure electron transfer for varied layer numbers.

Main Results:

• Graphene's basal planes show significant electron transfer activity for ferricyanide, hexaammineruthenium, and hexachloroiridate.
• No clear trend in kinetics with flake thickness was observed.
• Significant variation in kinetics across the basal plane indicates local surface condition effects.
• Atmosphere-aged graphite showed deteriorated kinetics compared to freshly exfoliated surfaces.

Conclusions:

• Graphene exhibits notable electrochemical reactivity, influenced by local surface conditions.
• Electron transfer kinetics are mediator-dependent and vary across graphene surfaces.
• Surface aging significantly impacts the electrochemical performance of carbon materials.