NUMERICAL SIMULATION OF ANODIC REACTIONS

摘要

Two electrochemical systems have been simulated, with a focus on the anodic reactions and associated phenomena. These systems are the Scanning Reference Electrode Technique instrument, examining an anodically-polarized surface, and an electrospray ion source, operated in the positive ion mode. In both of these systems the region of interest is small (10-200 (μm). The numerical technique used in the simulation was able to incorporate: features as small as 0.5 μm; multiple reactions at the anode surface; and nonuniform surface properties. Ion transport was modeled by the Laplace equation, together with nonlinear concentration and activation polarization boundary conditions on electroactive surfaces. The Laplace equation was solved using a boundary integral analysis, and the nonlinear polarization equations were satisfied via either a successive-substitution (Picard) or a two-step Gauss-Seidel iterative technique. Successive iterations for the polarization were determined from the previous iteration's current density distribution. This iterative process continued until the change in the boundary potentials was less than a specified tolerance.