Why standard electrokinetic analysis often fails for nanostructured electrodes - Reviewing inhomogeneous electroactivity

The advancement of electrocatalysis from fundamental research to application is a process that requires researchers from different fields to co-work seamlessly to be effective. In this mini review, we highlight common problems that are faced when the complexity of novel electrode assemblies, consisting of nanostructured materials, is moved from a fundamental view towards an evaluation for application. When the classical kinetic descriptors such as Butler-Volmer kinetics are applied to complex electrode assemblies, a clear distinction and attribution of material properties versus electrode performance becomes challenging. We emphasize recent advancements to discern and analyse electrocatalysis at composite or nanostructured electrodes. We discuss the origins of inhomogeneities in the electrocatalytic activity of three-dimensional electrodes, how these can be detected and which necessary changes from the classical methods, such as Tafel analysis, can be performed to ensure a sound data acquisition and evaluation.