Simulating electric field and current density in nanostructured electrocatalysts

The electrocatalytic performance of nanostructured heterogeneous electrocatalysts can be tailored by adjusting their geometries due to the morphologically dependent physicochemical effects, such as field-induced reagent concentration near high-curvature nanoscale features and the confinement of reaction intermediates in a nanocavity. However, the theoretical studies on these physicochemical effects in various nanoscale structures are considerably less common in comparison to the density functional theory calculations on the atomic structure design due to the absence of consistent simulation protocols in this area. This tutorial review presents the theory, models, and protocols for the simulation of the electrochemical properties of nanoelectrocatalysts with complex morphologies using the finite element method (FEM), including the local electric field (E-field) and the current density in the electrolyte adjacent to the electrode (J_electrolyte) and in the electrode (J_electrode). In the E-field simulation, we demonstrate the significant screening effect of the EDL on the E-field distribution as well as the influence of the relative permittivity of the electrolyte on the screening strength. In the J_electrolyte simulation, we illustrate the impact of the electrode kinetics on the electron transfer, which can significantly affect the J_electrolyte profile. In the J_electrode simulation, we reveal that the J_electrode crowding can occur in constricted areas of nanostructures, which would cause the structural transformation via electromigration. Finally, we discuss the applicability and limitations of the theoretical models discussed in this tutorial, suggesting the focus of future work to develop advanced multiscale modelling approaches. We hope this tutorial will assist electrochemists in navigating how to conduct accurate electrochemical physics effect simulations for analyzing the catalytic performance of nanoelectrocatalysts and thereby contribute to a wider adoption of FEM simulations in the rational design of advanced electrocatalysts.