heterogeneous diffusion rate constant

in electrochemistry
Defined by the equation:
k d = I l n F c A
where the limiting currentI l is assumed to be due to the diffusion species of concentration c and of diffusion coefficientD. n is the charge number of the cell reaction written so that the stoichiometriccoefficient of this species is unity. A is usually taken as the geometric area of the electrode, and F is the Faraday constant.
Source:
PAC, 1974, 37, 499 (Electrochemical nomenclature) on page 513