(701h) Electrocatalysts for Oxygen Reactions

Reaction kinetics at the oxygen electrodes tend to be sluggish. Addressing the challenges of slow kinetics through better design of electrocatalysts is a major technical issue for energy generation and storage that involve oxygen and water in the reactions. We have worked on catalysts for oxygen reduction reaction (ORR) in hydrogen fuel cells and oxygen evolution reaction (OER) in electrolyzers for direct water splitting in recent years. On the ORR electrocatalysts, both faceted alloy-based low-platinum group metal (PGM) PGM and metal organic framework (MOF)-derived non-PGM catalysts were developed. The post-synthesis processing was shown to be an effective way to optimize the nanostructures for high performance [1]. In situ characterization tools such as liquid flow cell techniques for transmission electron microscopy (TEM) show to be quite helpful to understand the design of faceted low-PGM catalysts [2-3]. On the OER catalysts, oxygen-deficient perovskites and various pyrochlores were examined for their performance in both alkaline and acidic media [4-6]. While most of the performance data presented in this talk were based on rotating disk electrode (RDE) technique, membrane electrode assembly (MEA) studies certain studies were performed. Among the techniques and methods, X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) were used in the structural analysis, while density functional theory (DFT) calculations added to the atomistic understanding of activity and stability.

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5. J. M. Kim,^# P.-C. Shih,^# K.-C. Tsao, Y.-T. Pan, X. Yin, C.-J. Sun, H. Yang, J. Am. Chem. Soc., 2017, 139, 12076-12083.
6. J. M. Kim, X. X. Chen, Y.-T. Pan, P.-C. Shih, H. Yang, J. Electrochem. Soc., 2017, 164, F1074-F1080.