Modeling Ceria-Based Nanomaterials for Catalysis and Related Applications

Abstract

Ceria (CeO2) is used as support material in heterogeneous catalysts since decades and, recently, ceria itself was also demonstrated to be catalytically active for some reactions. Atomistic and electronic structure details of the functioning of ceria in catalysis can nowadays be successfully uncovered with the help of computational modeling based on the density functional theory (DFT). Yet, the majority of such computational studies undertaken so far relied on extended models of surfaces, which are adequate for the description of surface science processes and phenomena, but neglect the nanostructured nature of ceria in many catalysts. This Perspective focuses on discussing DFT calculations of various nanostructured models of ceria and its composites relevant for catalysis. Pivotal consequences of ceria nanostructuring for its role in catalysts derived from the computational studies are documented and supported by experimental results. The presented case studies shed light on several actively debating issues of ceria usage in catalysis and other applications. For instance: What makes ceria nanoparticles in a certain size range dramatically more reactive in oxidative processes? Is the oxygen storage capacity of ceria solely due to its ability to easily form and heal oxygen vacancies or do alternative mechanisms also operate at the nanoscale? How prone are metal particles deposited on ceria to sintering or dispersion and how is this interplay controlled by the nanostructuring of the support? Under what conditions will the transfer of lattice oxygen atoms from ceria support to the metal particles deposited thereon become energetically favorable? How can the electron transfer across the metal-ceria interface be measured and its peculiarities rationalized? The discussed examples show that accounting for ceria nanostructuring in catalysts is essential for performing trustworthy computational modeling. Such realistic description is possible thanks to a variety of the recently developed dedicated models representative of ceria at the nanoscale.