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 activity of the functional component. Specifcally, we use molecular dynamics (MD) 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 sacrifcial barrier, is able to withstand 40.1 GPa 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, modelling reveals the deformation mechanisms and the importance of microstructural features, insights that are difficult to measure experimentally.