DIFFUSION TOWARD FRACTAL, INTERFACES POTENTIOSTATIC, GALVANOSTATIC, AND LINEAR SWEEP VOLTAMMETRIC TECHNIQUES

Diffusion to fractal electrodes has been investigated by three differe nt techniques for the oxidation of ferrocyanide in a gel electrolyte: the current response to a potential step, the potential response to a current step, and the current response to a linearly increasing potent ial. The current density us. time relationship under potentiostatic co ntrol, the transition time vs. current density under galvanostatic con trol, and the peak current density vs, sweep rate in a voltammetric ex periment all followed power laws similar to those describing the exper iments carried out with a planar electrode. The usual -0.5 exponent, h owever, became -(d-1)/2 in the case of a fractal electrode of dimensio n d. The experimental results were analyzed and described by solving a generalized diffusion equation involving a fractional derivative oper ator.