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Dynamic Imaging of Ostwald Ripening by Environmental Scanning Transmission Electron Microscopy
Author(s) -
Martin Thomas E.,
Gai Pratibha L.,
Boyes Edward D.
Publication year - 2015
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201500830
Subject(s) - ostwald ripening , catalysis , transmission electron microscopy , nanoparticle , scanning transmission electron microscopy , chemical engineering , materials science , scanning electron microscope , nanotechnology , sintering , chemical physics , chemistry , organic chemistry , metallurgy , composite material , engineering
The first dynamic atomic resolution environmental scanning transmission electron microscope (ESTEM) study of the nanoparticle sintering of a model Cu system is reported. ESTEM confers the advantage of a Z‐contrast dependence in industrially representative conditions to provide enhanced visibility of sub‐nanometer particles when compared with TEM. The importance of this is demonstrated by the significant enhancement in the Ostwald ripening rate of model Cu nanoparticles in the presence of 3 Pa hydrogen, an effect that is independent of the substrates studied. Temperatures of 400–550 °C are shown to switch the operating regime of the rate‐limiting mechanism. Cu catalysts are used for methanol synthesis and hydrocarbon‐conversion processes for fuel cells, and the importance of observing these catalysts in their working states is demonstrated. Unique ESTEM observations of Ostwald ripening are combined with kinetic models to improve the technical understanding of catalyst deactivation mechanisms.