Computer simulation of charge-selective electrochemistry of catechols at high-surface-area carbon fibers

The shape and size of cyclic voltammetric (CV) waves at the ultrahigh surface area carbon fiber are dependent on the pH and the charge of the electroactive species. The high surface area resulted from the fiber being fractured by application of a high anodic potential or current. The CV waves have been computer simulated with a model that assumes the entry of positively charged and, in some cases, neutral ones, but rejection of negatively charged species from the interior of the fractured fibers. Best fit between the computer-calculated and experimental CV waves is obtained for a model containing three components as the source of the current:  (a) background capacitive charge, (b) diffusion to the outer cylindrical-shaped fiber, and (c) interior thin-layer volume. Simulation results indicate that the values for the inner void volume are in the nanoliter range when electroactive species penetrate the interior.