Diffusional Voltammetry in Finite Spaces

The pore structure is a key design parameter for optimizing electrocatalytic systems that utilize porous electrodes, necessitating characterization at scales relevant to catalysis (∼0.1-100 μm). In this Review, we examine how diffusion during faradaic processes is impacted by the electrode pore geometry, defined by the concavity/convexity of its surface curvature, and by pore size, defined by the finiteness of the diffusion domain. We briefly outline experimental considerations for correlating experimental and simulated data from porous electrodes, and then outline the current theories for modeling diffusional voltammetry at various electrodes with finite diffusion spaces (direct problem), including planar redox-active films, concave inverse opals and hollow tubes, and convex pillar arrays and particle arrays. Finally, we describe how these theoretical frameworks can be applied to characterize the electrode pore structure by analyzing experimental voltammetric current responses (inverse problem).