Theoretical Analysis of Microelectrode Arrays under Forced Convection

Abstract

Numerical solutions to the equation that governs steady-state mass transport to a hexagonal array of small redox-active disks embedded in an otherwise inert rotating disk electrode, RDE, under both diffusion-limited and mixed, first order kinetic control were obtained using COMSOL. Analytical expressions were found, which accurately reproduced the simulations, yielding, for limiting cases, a behavior in agreement with that reported in the literature. This formalism was applied to the analysis of thin films of nanoparticles dispersed in inert high area supports attached to the surface of an inactive RDE. The results obtained made it possible to verify that, at loadings within the range of relevance to electrocatalyic materials for low temperature fuel cells, the use of a modified Koutecky-Levich-like equation for determining rate constants of first order redox processes is indeed warranted.