Protecting Ceria NanocatalystsThe Role of Sacrificial Barriers

Forces acting on
a functional nanomaterial during operation can
cause plastic deformation and extinguish desirable catalytic activities.
Here, we show that sacrificial materials, introduced into the catalytic
composite device, can absorb some of the imposed stress and protect
the structural integrity and hence the activity of the functional
component. Specifically, we use molecular dynamics to simulate uniaxial
stress on a ceria (CeO2) nanocube, an important functional
material with respect to oxidative catalysis, such as the conversion
of CO to CO2. We predict that the nanocube, protected by
a “soft” BaO or “hard” MgO sacrificial
barrier, is able to withstand 40.1 or 26.5 GPa, respectively, before
plastic deformation destroys the structure irreversibly; the sacrificial
materials, BaO and MgO, capture 71 and 54% of the stress, respectively.
In comparison, the unprotected nanoceria catalyst deforms plastically
at only 2.5 GPa. Furthermore, modeling reveals the deformation mechanisms
and the importance of microstructural features, insights that are
difficult to measure experimentally.