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Visualization of the distribution of anatase and rutile TiO 2 crystals in Au/TiO 2 powder catalysts by STEM–EELS spectrum imaging
Author(s) -
Akita Tomoki,
Kohyama Masanori
Publication year - 2014
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.5582
Subject(s) - rutile , anatase , electron energy loss spectroscopy , catalysis , scanning transmission electron microscopy , materials science , transmission electron microscopy , analytical chemistry (journal) , chemical engineering , crystallography , nanotechnology , chemistry , photocatalysis , engineering , biochemistry , chromatography
Gold nanoparticles deposited on TiO 2 supports exhibit high catalytic activity for various chemical reactions such as low‐temperature CO oxidation. The catalytic performance is sensitive to the structure of the TiO 2 supports, as reported in the epoxidation of propylene. TiO 2 powder (P‐25), widely used as the support for metal catalysts, contains both anatase and rutile TiO 2 phases. It is important to distinguish these two crystalline phases at the nanoscale in order to understand the effect of the support structure in Au/TiO 2 catalysis. In this study, the two‐phase distribution is analyzed using scanning transmission microscopy–electron energy‐loss spectroscopy (STEM–EELS). The distribution is revealed through multilinear least‐squares fitting on the basis of the difference in the energy‐loss near‐edge structure. The results obtained indicate that Au particles are preferentially deposited on rutile TiO 2 in the deposition/precipitation process. The STEM–EELS spectrum imaging method, with its high energy and spatial resolutions, can be employed to determine the distribution of crystal phases, components, and valence states. Copyright © 2014 John Wiley & Sons, Ltd.