posted on 2021-01-28, 14:12authored byEthan
L. Lawrence, Barnaby D. A. Levin, Tara Boland, Shery L. Y. Chang, Peter A. Crozier
Oxygen vacancy creation and annihilation
are key processes in nonstoichiometric
oxides such as CeO2. The oxygen vacancy creation and annihilation
rates on an oxide’s surface partly govern its ability to exchange
oxygen with the ambient environment, which is critical for a number
of applications including energy technologies, environmental pollutant
remediation, and chemical synthesis. Experimental methods to probe
and correlate local oxygen vacancy reaction rates with atomic-level
structural heterogeneities would provide significant information for
the rational design and control of surface functionality; however,
such methods have been unavailable to date. Here, we characterize
picoscale fluxional behavior in cations using time-resolved in situ aberration-corrected transmission electron microscopy
to locate atomic-level variations in oxygen vacancy creation and annihilation
rates on oxide nanoparticle surfaces. Low coordination number sites
such as steps and edges, as well as locally strained sites, exhibited
the greatest number of cation displacements, implying enhanced surface
oxygen vacancy activity at these sites. The approach has potential
applications to a much wider class of materials and catalysis problems
involving surface and interfacial transport functionalities.