Steering Oxygen Reduction Electrocatalysts toward 4e/4H Pathway using a Hybrid Membrane with Fuel Cell Implications

Abstract

<p>Proton-coupled electron transfer (PCET) processes are instrumental to catalytic reactions and energy applications. In this talk, I will showcase our efforts in designing and constructing a nanoscale electrochemical platform (see figure) to modulate the proton and electron transfer rates independently for oxygen reduction reaction (ORR). ORR is the reaction that limits the performance of fuel cells and related energy conversion technologies. Our electrocatalytic nanoplatform features a hybrid bilayer membrane (HBM) comprising of a self-assembled monolayer (SAM), an ORR catalytic motif, a phospholipid layer, and a proton transfer agent. 1 Each of these four controls one aspect of ORR, and together they dictate the overall catalytic performance. Utilizing this modular system, the electron transfer rate can be adjusted by the SAM length, and the proton transfer rate can be tuned by the proton transfer agent in the lipid layer. 2 By regulating the relative rates of proton and electron transfer using our nano-architecture, we achieve higher selectivity for the four-electron process to generate water as the desired product without compromising the activity of the electrocatalyst. 3 New data will also be presented on triggering proton delivery against a pH gradient. 4 In summary, our electrochemical system will provide unique insights into the optimal thermodynamic and kinetic parameters not only for ORR catalysts, 5 but also offer new opportunities to enhance the performance of other catalysts involved in fuel generation and energy storage. 6<br></p>