DIGITAL-SIMULATION OF STEADY-STATE AND NONSTEADY STATE VOLTAMMETRIC RESPONSES FOR ELECTROCHEMICAL REACTIONS OCCURRING AT AN INLAID MICRODISK ELECTRODE - APPLICATION TO EC(IRR), EC' AND CE 1ST-ORDER REACTIONS

A general algorithm based on the Hopscotch method and a conformal map is used to treat electrochemical reactions with coupled homogeneous ch emical reactions occurring both at conventionally sized electrodes and at ultramicroelectrodes. A change of the dimensionless parameter p = a(nFv/RTD)1/2, where a is the radius of the electrode, v the potential sweep rate and D the diffusion coefficient, allows us to describe pro perly the planar and the convergent mass transfer to an inlaid disk-sh aped electrode. The dimensionless parameter lambda'= ka2/D, which is a function of the sum of the chemical rate constants (k) and of the ele ctrode radius, describes the kinetics and may be used instead of the c onventional parameter lambda = k(RT/nFv). A suitable choice of the spa ce-time grid gives accurate results, even for kinetic problems affecte d by stiffness difficulties. The adequacy of the implementation is est ablished by comparison with known solutions relative to the EC(irr') E C' and CE mechanisms for two limiting cases, i.e. planar and radial ma ss transport conditions.