Adaptative finite element simulation of currents at microelectrodes to a guaranteed accuracy. First-order EC ' mechanism at inlaid and recessed discs

In this paper we extend the introductory work described in the accompanying papers on the use of adaptive finite element methods in electrochemical si mulation (K. Harriman et al., Electrochem. Commun. 2 (2000) 150 and 157) to the case of a (pseudo) first-order EC' reaction mechanism at both an inlai d and a recessed disc. The recessed disc is shown to be a particularly suit able example for illustrating the power of the technique in providing the s imulated current to a guaranteed accuracy on near-optimal meshes. For both problems we demonstrate that we can obtain excellent accuracy across the sp ectrum of reaction rates using just a few seconds of CPU time. Our results also confirm the accuracy of some recently published analytical solutions t o these problems (L. Rajendran, M.V. Sangaranarayanan, J. Phys. Chem. B 103 (1999) 1518-1524; J. Galceran et al., J. Electroanal. Chem. (1999) in pres s). (C) 2000 Elsevier Science S.A. All rights reserved.