Communication—Demonstrating the Role of Mass Transport in Double Layer Formation

Abstract

Herein we present insight into the structure and behaviour of the electrified interface formed between a planar non-porous glassy carbon electrode and an aqueous solution of 0.5 M Na2SO4. Specifically, a glassy carbon rotating disk electrode was used to show correspondence between a decreasing rotation rates, and hence a decreasing boundary layer thickness, with a decreasing interfacial capacitance. The implication is that electrolyte counter charge is being dissipated by convective flow outside of the boundary layer. With the boundary layer thickness being macroscopic, it is clear that electrolyte counter-charge extends a substantial distance into the electrolyte.

Electrode Spacing Effects on the Capacitance of Glassy Carbon Electrodes in Aqueous Electrolytes

“…26 Most recently, this was again validated by rotating disk electrode voltammetry, in which case the thickness of the stagnant layer, as determined by the electrode rotation rate, influenced interfacial capacitive charge storage. 27 If the diffuse layer was as thin as predicted by Eq. 3, then electrode rotation should not have had any effect on performance whatsoever.…”