(684f) Design of Ruddlesden-Popper Oxides with Optimal Activity for Surface Oxygen Exchange and Electrochemical Oxygen Reduction

Implementation of efficient energy conversion systems (i.e., solid oxide fuel cells) are of high importance due to the rapid depletion of nonrenewable energy sources. Oxygen reduction reaction (ORR) plays an important role in the performance of these systems. Ruddlesden-Popper (R-P) oxides have shown promise as electrocatalysts for this reaction due to their excellent mixed ionic electronic conductivities and high electrocatalytic activity for surface oxygen exchange (the process that governs oxygen reduction in these materials).^1-3In this study, we combine density functional theory calculations along with controlled kinetic experimental studies on well-defined nanostructures of first-order R-P oxides of varying compositions to understand the underlying factors that govern their surface oxygen exchange kinetics and develop a structure-function relation that can guide the development of optimal R-P oxides for ORR. A series of R-P oxides with different compositions have been synthesized using a controlled reverse microemulsion approach. Isotopic labeled oxygen (¹⁸O₂) exchange and electrochemical oxygen reduction studies were used to investigate the effect of composition on the activity of these materials. The experimental results were compared to the computational findings. A structure-activity relation was developed providing insights into the optimization of complex mixed ionic-electronic oxides for oxygen reduction.

References

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