To validate the usefulness of in-situ environmental TEM (ETEM) in catalyst chemistry, several issues need to be addressed such as electron irradiation effects, heterogeneity of real catalysts, temperature and pressure gaps. These issues in ETEM observation can be settled in supported gold nanoparticulate catalysts (AuNP catalysts) by quantitative data analyses [1]. Based on the analyses, we have studied dynamic structures of AuNP catalysts.We used an ETEM [1] that is equipped with a corrector for the spherical aberration of the objective lens. The sample was Au/CeO2 powder that has exhibited high catalytic activity for the oxidation of CO even below room temperature [2].The quantitative analyses can confirm that an area of interest under atomic resolution ETEM observation acts as catalyst. The ETEM observation proved that catalytically active AuNPs move reversibly and stepwise by approximately 0.09 nm on CeO2 support surface at room temperature and in a reaction environment. The lateral displacements and rotations indicate that AuNPs are loosely bound to oxygen-terminated CeO2. The AuNPs are likely anchored to oxygen-deficient sites [3]. Observations indicate that the most probable activation sites in AuNP catalysts, which are the perimeter interfaces between an AuNP and a support, are not structurally rigid. We present more details on in-situ ETEM observation of the catalysts and others.References[1] S. Takeda et al., Microscopy. 62 (2013) 193-203.[2] T. Uchiyama et al., Angew. Chem. Int. Ed., 50 (2011) 10157-11600.[3] Y. Kuwauchi et al., Nano Lett. 13 (2013) 3073-3077.This study was partially supported by a Grant-in-Aid for Scientific Research (A) , Grant No. 25246003 from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

Catalytically active atomic-structures in metal nanoparticulate catalysts studied by  quantitative environmental TEM

248th National Meeting (2014)

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