DFT study of formation and migration of oxygen vacancies in mixed oxides: Ce1-xZrxO2 and Ni-Ce1-xZrxO2

OTERO, GUADALUPE SOL; ZIMICZ, M. GENOVEVA; LUSTEMBERG, PABLO; GANDUGLIA PIROVANO, M.V.

Santa Fé

Congreso; VI San Luis Conference on Surfaces, Interfaces and Catalysis; 2018

The mixed oxides of the Ce1-xZrxO2 system and the NiO+(Ce,Zr,Ni)O2 compoite are of interest due to their catalytic role in the production of H2, reforming and partial oxidation of hydrocarbons. Doping ceria with metals like Zr has been shown to improve redox properties and thermal stability of the oxide. A technological application of this kind of material is that of intermediate temperature solid oxide fuel cells (IT-SOFCs), specially on the fuel oxidation electrode (anode). Previous results indicate that in the CeO2-ZrO2 olid olution, even small Zr concentrations (less than 10%) decrease the bulk reduction energy values compared to that of pure ceria.In order to understand the reasons of this enhancement, we have performed a systematic DFT+U (density functional theory plus Hubbard correction parameter) analysis of both, the bulk and the (111) surface of Ce1-xZrxO2 oxide with the VASP code.This sistematic study has been repeated for the Ni-Ce1-xZrxO2 system in the limit of small concentration (less than 2%) with the aim of understanding the effects of the presence of Ni in the solid solution or at the surface on the atomic and electronic properties of these mixed oxides.