Lecture 2

Design and in situ characterization of catalysts and surfaces
including PEM Fuel cells

Yasuhiro Iwasawa

Department of Engineering Science, The University of Electro-Communications,
Chofu, Tokyo 182-8585, Japan

 Tremendous catalysis of surfaces and nanoparticles may be coupled with structural and electronic kinetics/dynamics and spatial distribution of active metals/ensembles in the catalytic materials. New strategy and concept based on understanding of those spatio-temporal issues by XAFS can lead to tailor-made catalyst design for a target reaction in green sustainable processes.^1-3) Dynamic structures of the catalysts relevant to selective catalyses in irreversible one-path chemical processes have successfully been characterized by in-situ time-resolved XAFS techniques at SPring8 and KEK-PF at a time resolution of 2 ms –1 s, depending on the reaction systems.^1,2) Besides time resolution, space-resolved XAFS can provide a new piece of information on catalyst behavior.³⁾ The talk documents real-time and real-space XAFS techniques for in situ characterization of typical selective catalysts, fuel cells, methane reforming, and oxygen diffusion. The advanced XAFS for catalysts themselves provides valuable information on catalysis mechanisms and rational design of catalysts, which is entirely different from that from reaction kinetics/dynamics of reactant/product molecules in gas phase. The in situ XAFS technique is useful particularly for characterization and understanding of environment-friendly proton-exchange- membrane fuel cells (PEMFC), which can be used in both fuel-cell automobiles and energy systems to address the serious environmental and energy problems faced by our modern society. For commercial applications, such as fuel-cell automobiles, systems with at least 10-times higher activity and efficiency are needed, but there is no recipe for design of good FC catalysts yet.

References

1. M. Tada, S. Murata, T. Asaoka, K. Hiroshima, K. Okumura, H. Tanida, T. Uruga, H. Nakanishi, S. Matsumoto, Y. Inada, M. Nomura, and Y. Iwasawa, Angew. Chem. Int. Ed. 46, 4310-4315 (2007).
2. M. Tada, Y. Uemura, R. Bal, Y. Inada, M. Nomura, and Y. Iwasawa, Phys. Chem. Chem. Phys., 12, 5701–5706 (2010).
3, M. Nagasaka, H. Kondoh, K. Amemiya, T. Ohta, and Y. Iwasawa, Phys. Rev. Lett., 100, 106101 1-4 (2008).