SEVENEN FRAMEWORK PROGRAMME

Design of thin-film nanocatalysts for on-chip fuel cell technology

Article UBCN - Phys. Chem. Chem. Phys.

O vacancies on steps on the CeO2(111) surface

A9-KozlovSM-grabstract.gif

Phys. Chem. Chem. Phys. 16, 7823 (2014) - read more on RSC pages

Sergey M. Kozlova and Konstantin M. Neymana,b,*

    a Departament de Química Física and Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, C/Martí i Franquès 1, 08028 Barcelona, Spain
    b Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain

Cerium dioxide is a compound important for heterogeneous catalysis, energy technologies, biomedical applications, etc. One of its most remarkable properties is low O vacancy (Ovac) formation energy Ef. Nanostructuring of ceria was shown to decrease Ef and to make the oxide material more active in oxidative reactions. Here we investigate computationally formation of Ovac on CeO2(111) surfaces nanostructured by steps with experimentally observed structures. To facilitate the search for Ovac + 2Ce3+ configurations that yield the lowest Ef values we proposed and employed an efficient computational scheme where DFT + U calculations were preceded by a pre-screening procedure based on the results of plain DFT calculations. Ef values on the steps were calculated to be up to 0.7 eV lower than on a regular CeO2(111) surface. Some energetically stable Ovac + 2Ce3+ configurations were found to include subsurface Ce3+ ions. The present results quantify to what extent the roughness of the CeO2(111) surface affects its reducibility.