Advanced spatio-temporal XAFS for catalyst surfaces and nanoparticles

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

Abstract
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. Dynamic structures of the catalysts relevant to selective catalyses 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. Besides time resolution, space-resolved XAFS can provide a new piece of information on catalyst behavior. The talk documents real-time and real-space XAFS techniques for in situ characterization of typical selective catalysts, fuel cells, oscillatory reactions, methane reforming, oxidative phase separation, oxygen diffusion, etc. 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.