Changes in electrodic reaction rates due to elastic stress and stress-induced surface patterns

This paper investigates the influence of elastic stresses and surface patterns on electrodic reaction rates. There are several well known processes that affect electrodic reaction rates such as rupture of passive layers, repassivation, and hydrogen adsoption, among others. Our main goal in this paper is to isolate the direct influence of elastic stresses and surface patterns on reaction rates. To this end, we propose an extended Butler-Volmer equation that incorporates the effect of stress and surface curvature on the chemical potential. The proposed extension of the Butler-Volmer equation is sensitive to both the magnitude and the tensile or compressive nature of the stress field. Our numerical studies show that, depending on the electrodic material, stress and surface curvature can produce a significant shift of the chemical potential, and hence, amplify or reduce electrodic reaction rates. We verified the shift in reaction rates predicted by our proposed continuum model using ab-initio electronic structure calculations. As an application of our proposed model, we demonstrate how a stress field in an electrodic domain may significantly affect the evolution of an anodic dissolution front. (c) 2013 Elsevier Ltd. All rights reserved.