Control of Material Microstructure of Materials for Electrochemistry and Obscurants

The manipulation of microstructures within modern micro- and nanomaterials stands as a prevalent practice with extensive applications across diverse fields. The deliberate control of material microstructures empowers the fine-tuning of their distinctive physical and chemical properties, catering to specific requirements in various applications. This dissertation mainly explores the strategic utilization of materials endowed with controlled microstructures, particularly investigating their significance and applications in the field of electrochemistry and obscurants.

Finding ways to reduce reactor volume while increasing product output for electroorganic reactions would facilitate the broader adoption of such reactions for the production of chemicals in a commercial setting. The goal of the electrochemistry research is to investigate how the use of flow with different electrode structures impacts the productivity (i.e., the rate of product generation) of a TEMPO-mediated azidooxygenation reaction. Comparison of a flow and batch process with carbon paper (CP) demonstrated a 3.8-fold higher productivity for the flow reactor. Three custom carbon electrodes, sintered carbon paper (S-CP), carbon nanofiber (CNF), and composite carbon microfiber-nanofiber (MNC), were studied in the flow reactor to evaluate how changing the electrode structure affected productivity. Under the optimum conditions these electrodes achieved productivities 5.4, 6.5 and 7.8 times higher than the average batch reactor, respectively. Recycling the outlet from the flow reactor with the MNC electrode back into the inlet achieved an 81% yield in 36 minutes, while the batch reactor obtained a 75% yield in 5 hours. These findings demonstrate that the productivity of electroorganic reactions can be substantially improved through the use of novel flow-through electrodes. Further exploration on other type of electroorganic reaction with 3-D porous electrode, like electrochemical cross-electrophile coupling (XEC), got an extensively lower yield in the flow cell with different configurations, which was due to the pass of chemicals through membrane in divided cell and low residence time in undivided cell. Due to the time and funding limited, we did not dig deeper into this project.

The ultimate goal of the obscurants work is to create an engineered aerosol that acts as one-way smoke, i.e., it creates an asymmetric vision environment in which the ability to image objects depends on the viewing direction. To this end I developed a rapid, one-pot synthesis of copper-based microclubs that consist of a Cu2O octahedron attached to a Cu2O@Cu shaft. Millions of synthesized particles were analyzed in minutes with a FlowCam to provide a robust statistical analysis of their geometry, and rapidly elucidate the roles of the reaction constituents on the particle shape and yield. By utilizing Bayesian Optimization, the parameter space of the reaction conditions was fully explored, reducing the mean square error (MSE) between predicted and actual yield by 125 times after 14 iterations and achieving 64% yield of microclub production in 20 mL scale. With the slight modification on the optimized conditions, 67% yield was achieved under 2 L scale synthesis of microclub. The combination of asymmetry in both shape and composition introduces a 30% difference in scattering of light propagating parallel to the microclub axis from opposing directions. This work represents a first step toward the creation of an asymmetric imaging environment with an aerosol consisting of acoustically aligned microclubs.