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 simulation (K. Harriman et al., Electrochem. Commun. 2 (2000) 150 and 157) to the case of a (pseudo) firstorder ECʹ reaction mechanism at both an inlaid and a recessed disc. The recessed disc is shown to be a particularly suitable example for illustrating the power of the technique in providing the simulated current to a guaranteed accuracy on near-optimal meshes. For both problems we demonstrate that we can obtain excellent accuracy across the spectrum of reaction rates using just a few seconds of CPU time. Our results also confirm the accuracy of some recently published analytical solutions to these problems (L. Rajendran, M.V. Sangaranarayanan, J. Phys. Chem. B 103 (1999) 1518¯1524; J. Galceran et al., J. Electroanal. Chem. (1999) in press).