During the last few decades, materials scientists have made notable advances in the development of ordered porous materials for catalysis, energy, separations, and biological applications. However, a key remaining challenge is the development of scalable techniques to manufacture self-standing hierarchically organized porous materials. State-of-the-art electrochemical devices (e.g. fuel cells, redox flow batteries, metal-air batteries) use porous materials with poorly defined three-dimensional microstructures, leading to limitations in performance. Novel applications require the development of materials with sophisticated control over the architecture at different length-scales. For example, selecting an adequate average pore size, porosity, and tortuosity would reduce pressure drop losses, improve mass transport and reaction distribution, decrease ohmic resistance, and maintain a low weight. We develop fabrication techniques to prepare architected materials with various degrees of hierarchical organization.
The interfacial properties of solids and the interacting fluid define a number of important characteristics, such as electrochemically-active surface area, intrinsic activity, and wettability. Commonly used polymeric coatings are generally applied using dip-coating processes, and therefore lack accurate control over the distribution and morphology. In this thrust, we are interested in obtaining structure-function relationships, using well-defined model systems, to fundamentally understand the role of surface chemistry and morphology on the physicochemical and electrochemical properties. We employ electrografting and other techniques to grow thin films of selected polymers with tailored properties onto the surface of model electrodes and porous materials.
Electrochemical diagnostics are based on measuring the voltage response to an applied current (or vice versa). However, our ability to deconvolute the underlying thermodynamic, kinetic, and transport processes is still quite limited and is often challenged by the interdependence of multiple processes on the same few variable parameters. We are interested in understanding the performance of porous materials during operation through visualization of local properties (e.g. concentration, temperature). Pursuant to this goal, we employ advanced imaging techniques, namely neutron imaging, and X-ray tomographic microscopy, to visualize the solid morphology and the distribution of flow during operation.