Increased electron transfer kinetics and thermally treated graphite stability through improved tunneling paths

Aging of graphite-based materials results in slower heterogeneous electron transfer (HET) kinetics and limits their conducting and catalytic performance. A thermal treatment protocol reportedly maintained a high HET kinetics of graphite by at least nine weeks. The present report investigates the consequences of such HET increases on graphite stabilities. Raman 2D peak evolution, potential windows, EIS, optical AFM, chronoamperometry and potentiodynamic polarization studies were employed to investigate electrochemical, structural and corrosion stabilities and mechanisms of the pristine and thermally treated graphite as they relate to its HET kinetics. Structure-induced electronic changes are suggested to trigger improved tunneling paths through the interfaces from the bulk layer. This tunneling improves and sustains HET kinetics by orders of magnitude in the treated graphite. Except for the graphite fibers, thermal treatment increased HET kinetics without compromises to electrochemical, structural and corrosion stabilities. In most instances, these properties improved over the pristine graphite.

Thermal treatment transforms the pristine graphite into well-ordered lattices. AFM images show visual indifference between the pristine and treated graphite. However, their electronic structures and resultant electrochemistry are different. Despite minimal energy differences between both structures, a large thermodynamic barrier hinders the reversal of the treated to the pristine-like state.