AUTHOR=Kim Byung-Hyun , Kullgren Jolla , Wolf Matthew J. , Hermansson Kersti , Broqvist Peter TITLE=Multiscale Modeling of Agglomerated Ceria Nanoparticles: Interface Stability and Oxygen Vacancy Formation JOURNAL=Frontiers in Chemistry VOLUME=7 YEAR=2019 URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00203 DOI=10.3389/fchem.2019.00203 ISSN=2296-2646 ABSTRACT=

The interface formation and its effect on redox processes in agglomerated ceria nanoparticles (NPs) have been investigated using a multiscale simulation approach with standard density functional theory (DFT), the self-consistent-charge density functional tight binding (SCC-DFTB) method, and a DFT-parameterized reactive force-field (ReaxFF). In particular, we have modeled Ce40O80 NP pairs, using SCC-DFTB and DFT, and longer chains and networks formed by Ce40O80 or Ce132O264 NPs, using ReaxFF molecular dynamics simulations. We find that the most stable {111}/{111} interface structure is coherent whereas the stable {100}/{100} structures can be either coherent or incoherent. The formation of {111}/{111} interfaces is found to have only a very small effect on the oxygen vacancy formation energy, Evac. The opposite holds true for {100}/{100} interfaces, which exhibit significantly lower Evac values than the bare surfaces, despite the fact that the interface formation eliminates reactive {100} facets. Our results pave the way for an increased understanding of ceria NP agglomeration.