Direct visualization of electrochemical reactions and heterogeneous transport within porous electrodes in operando by fluorescence microscopy
By Wong, Andrew A.; Rubinstein, Shmuel M.; Aziz, Michael J.
Published in Cell Reports Physical Science
2021
Abstract
Summary Optical fluorescence microscopy is shown to enable both high spatial and temporal resolution of redox-dependent fluorescence in flowing electrolytes. We report the use of fluorescence microscopy coupled with electrochemistry to directly observe the reaction and transport of redox-active quinones within porous carbon electrodes in operando. We observe surprising electrolyte channeling features within several porous electrodes, leading to spatially distinguishable advection-dominated and diffusion-dominated regions. These results challenge the common assumption that transport in porous electrodes can be approximated by a homogeneous Darcy-like permeability, particularly at the length scales relevant to many electrochemical systems such as redox flow batteries. This work presents a new platform to provide highly resolved spatial and temporal insight into electrolyte reactions and transport behavior within porous electrodes.