CeO2(111) defect structure, oxygen migration and polaron hopping: A theoretical perspective

M. V. GANDUGLIA PIROVANO; G. E. MURGIDA; V. FERRARI; A. M. LLOIS; D. ZHANG; Z.-K. HAN; Y. GAO

Congreso; DPG Spring Meeting of the Condensed Matter Section (SKM) together with the EPS; 2018

Deep understanding of the defect structure of ceria(CeO2) surfaces isessential to tailor their functionality in applications. For the CeO2(111)surface, whether surface oxygen vacancies attract or repel, and whetheroxygen migration and polaron (Ce3+) hopping are entangled, are heavilydebated. Also, a number of surface reconstructions have been observedupon reduction, but their structures have remained elusive.Here, supported by density-functional theory-based modeling, statisticalthermodynamics, Monte Carlo and molecular dynamic simulations,and experimental results, we elucidate: (𝑖) the subsurface preferenceat low vacancy concentration and temperature [1,2], (𝑖𝑖) the formationof surface vacancy clusters with increased degree of reduction andtemperature [2], (𝑖𝑖𝑖) the nature of the observed (?ã7?~?ã7)𝑅19.1∘,(?ã7?~3)𝑅19.1∘, (?ã3?~?ã3), (3?~3), and (4?~4) reconstructions [3], aswell as (𝑖𝑣) the role of Ce3+ ions in oxygen vacancy migration [4].[1] G. E. Murgida, M. V. Ganduglia-Pirovano, Phys. Rev. Lett. 110.246101 (2013).[2] Z.-K. Han et al., submitted to Phys. Rev. Materials (2017).[3] R. Olbrich et al. J. Phys. Chem. C, 121, 6844 (2017).[4] D. Zhang et al. in preparation.