Designing Hybrid Electrodes to Dictate Oxygen Reduction Product Selectivity

Abstract

Reactions involving protons and electrons are central to many catalytic processes and energy applications. In this talk, I will describe my laboratory’s efforts in developing a nanoscale organic-inorganic hybrid electrochemical platform to modulate independently the proton and electron transfer rates for oxygen reduction reaction (ORR). ORR is the chemical reaction that critically limits the performance of fuel cells and related energy conversion technologies. Our nanoscale electrochemical platform features a hybrid bilayer membrane (HBM) comprising of a self-assembled monolayer (SAM), an azide-alkyne click moiety, an ORR electrocatalyst, a phospholipid layer, and a proton transfer agent [1]. Each of these five controls one aspect of ORR, and together they determine the overall catalytic performance. Utilizing this modular nanosystem, the electron transfer rate can be adjusted by changing the SAM length, and the proton transfer rate can be tuned by the proton transfer agent in the lipid layer. The click moiety further allows for efficient attachment of various electrocatalytic units with other functionalities. By regulating the relative rates of proton and electron transfer using our hybrid electrode architecture, we achieve higher selectivity for the four-electron process to generate water as the desired product without compromising the activity of the electrocatalyst. New data will also be presented to facilitate cross-discipline discussions on simulations for rational materials design. In summary, our hybrid electrode system will provide unique insights into the optimal thermodynamic and kinetic parameters not only for ORR catalysts, but also offer new opportunities to enhance the performance of other catalysts for fuel generation and energy storage.