Bridging the scales within transport-coupled kinetic models for heterogeneous electrocatalysis

Optimizing reaction rates in heterogeneous electrocatalysis requires a solid, fundamental understanding of the interplay between mass transport and the intrinsic reaction kinetics at the electrode surface. As these processes occur on disparate scales, however, bridging the two into a (single) comprehensive reaction model is a challenging task and active area of research. In this perspective, we give a current overview of transport-coupled kinetic models while making a distinction between those that describe the surface reaction via an effective phenomenological or first-principles based kinetic model. This choice tends to be accompanied by a correspondingly more or less elaborate inclusion of mass transport. The two modeling approaches thus generally differ in the scientific questions that they aim to answer; whether focusing on elaborate transport effects and resulting design rules at the device level or more detailed mechanistic insight on a microscopic scale. We first discuss these approaches separately, including their pros and cons through notable studies in the existing literature, and conclude with an outlook view on combining the value of both in future research.