Ab initio investigation of the formation of ZrO2-like structures upon the adsorption of Zr-n on the CeO2(111) surface

Author(s)

Mucelini, Johnatan ^[1] ; Costa-Amaral, Rafael ^[1] ; Seminovski, Yohanna ^[1] ; Da Silva, Juarez L. F. ^[1]

Affiliation

^[1] Univ Sao Paulo, Sao Carlos Inst Chem, POB 780, BR-13560970 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Journal of Chemical Physics; v. 149, n. 24 DEC 28 2018.
• Web of Science Citations: 1

Abstract

The adsorption of Zr on the CeO2 surfaces can lead to the formation of ZrO2-like structures, which can play a crucial role in the catalytic properties of CexZr1-xO2 as support for transition-metal catalysts; however, our atomistic understanding is far from satisfactory, and hence, it affects our capacity to engineer the combination of ZrO2-CeO2 for catalysis applications. Here, we investigate the adsorption of Zr-n (n = 1 - 4) atoms on CeO2(111) surfaces through density functional theory with the Hubbard model and bring new insights into the Zr-CeO2 interaction and the formation of ZrO2-like structures on ceria. We found that the Zr atoms oxidize to Zr4+ and strongly interact with the O2- anions, reducing the surface Ce4+ cations to Ce3+ (4 Ce atoms per Zr adatom), which stabilizes the system by more than 10 eV per Zr. As more Zr is adsorbed, the O2- species migrate from the sub-surface to interact with the on-surface Zr adatoms in hcp sites, producing a full ZrO2-like monolayer, which contributes to reduce the strain induced by the increased size of the Ce3+ cations compared with Ce4+. The simulated partial and full ZrO2-like structure thicknesses agree with the experimental measurements. In addition, we found an unprecedented trend for the on-surface Zr atoms: our calculations show that they are less stable than Zr replacing Ce3+ atoms from the first cation layer. Therefore, under sufficiently high temperatures, one expects the formation of a Ce2O3-like/c-ZrO2/CeO2 structure, which may completely change the reactivity of the surface. Published by AIP Publishing. (AU)

• FAPESP's process: 17/11631-2 - CINE: computational materials design based on atomistic simulations, meso-scale, multi-physics, and artificial intelligence for energy applications
• Grantee: Juarez Lopes Ferreira da Silva
• Support Opportunities: Research Grants - Applied Research Centers Program
• FAPESP's process: 14/02213-4 - A DENSITY FUNCTIONAL THEORY INVESTIGATION OF THE INTERACTION OF WATER AND ETHANOL WITH TRANSITION -METAL CLUSTERS SUPPORTED ON THE CeO2(hkl) SURFACES
• Grantee: Yohanna Seminóvski Pérez
• Support Opportunities: Scholarships in Brazil - Post-Doctoral