Scanning electrochemical microscopy (SECM) yields two-dimensional electrochemical images when the current at a microelectrode is recorded as it moves above a surface generating redox species. As SECM images are often systematically compared to microstructure features obtained by electron microscopy there is a clear need to find ways to integrate electron microscopy images into SECM image simulations.

Recently, finite element method simulations of sites where electrochemical reactions take place is employed to evaluate reactive feature size.[1] Current models move the microelectrode or the reacting surface, continuously changing the geometry of the simulation and thus requiring re-meshing, which increases the computation time.

We present a modeling approach by which SECM images of arbitrarily-shaped reactive sites can be simulated using a grid of pixels that can be turned ‘on’ and ‘off’ using COMSOL^® multiphysics. Specifically, COMSOL^®’s Java API is used to change the selection of pixels that are turned ‘on’ to simulate the movement of the electrode without changing the geometry of the simulation. The mesh can be re-used for each data-point in the image, dramatically reducing the time needed to simulate SECM images. This work also presents a mostly automated workflow for using an electron microscopy image of a reactive site to determine which pixels should be turned ‘on’ and fitting the kinetics at these pixels by simulating their SECM image.

[1] L. I. Stephens, N. A. Payne, S. A. Skaanvik, D. Polcari, M. Geissler, J. Mauzeroll, Evaluating the Use of Edge Detection in Extracting Feature Size from Scanning Electrochemical Microscopy Images. Analytical Chemistry 2019, 91, 3944-3950.