Raman Spectra of Polycrystalline CeO2: A Density Functional Theory Study

Abstract

Cerium oxide is an important material for catalytic and fuel cell applications. We present an ab initio density functional theory (DFT) study of the vibrational properties of ceria focusing on the interpretation of Raman spectra of polycrystalline powder samples, with vibrational bands in the frequency region between 250 and 1200 cm–1. The model systems include the oxidized CeO2 as well as the reduced CeO2–x and Ce2O3 bulk materials together with the CeO2(111) and oxygen defective CeO2–x(111) surfaces. The experimentally observed band at 250 cm–1 is assigned to a surface mode of the clean CeO2(111) surface, in agreement with our Raman spectra of ceria (CeO2) powders with varying crystal size (Filtschew, A.; Hofmann, K.; Hess, C., J. Phys. Chem. C 2016, 120, 6694). The reduced model systems display signature vibrational bands in the 480–600 cm–1 region associated with the presence of oxygen defects and reduced Ce3+ ions. In the high-frequency region between 800 and 900 cm–1, characteristic peroxide (O22–) ...