EIS at carbon fiber cylindrical microelectrodes

The theoretical mass-transport impedance at cylindrical microelectrodes has been known for some time, but an experimental verification is given here for the first time, using carbon fiber electrodes taken from a commercial carbon felt. Nonlinear least-squares fitting of the impedance spectrum of a redox couple at the reversible potential enables accurate evaluation of a composite parameter containing the standard rate constant and mean diffusivity, without measuring the fiber diameter, length or area.