Oxygen Vacancy-Related Cathodoluminescence Quenching and Polarons in CeO₂

Abstract

We used cathodoluminescence (CL) spectroscopy to characterize the oxygen vacancies (V O ) in ceria (CeO 2 ). The effects of the processing atmosphere and thermal quenching temperature on the nature and distribution of the intrinsic defects and on the spectroscopic behavior were investigated. The presence of polarons and associates of the polarons with the oxygen vacancies such as (V O •• –Ce Ce ′ ) • is demonstrated. CL intensity quenching above a critical concentration of V O has been shown. Even though the emission centers in all samples are the same, their concentration changes with the oxygen partial pressure of the processing atmosphere. Deconvolution of the observed CL spectra shows that the emissions originating from the F 0 centers prevail over those of F + centers of V O when the defect concentration is high.

Tiny Species with Big Impact: High Activity of Cu Single Atoms on CeO2–TiO2 Deciphered by Operando Spectroscopy

“…Interestingly, raising the Cu content in Cat2 above that of Cat1 lowers the intensity of the O 2 •– signal. This may be due to the formation of EPR-silent doubly charged oxygen vacancies (V O •• ) since Ce 3+ could transfer two 4f electrons to the adsorbed O 2 , forming EPR-silent peroxide species upon interaction with O 2 . Using the density functional theory calculation, Zhao et al found that O 2 •– with lower adsorption energies are less stable than peroxides and thus could be easy to transform into the more stable peroxide species.…”

“…•− signal. This may be due to the formation of EPR-silent doubly charged oxygen vacancies (V O •• ) 121 since Ce 3+ could transfer two 4f electrons to the adsorbed O 2 , forming EPRsilent peroxide species upon interaction with O 2 . 122 Using the density functional theory calculation, Zhao et al 122 found that O 2…”

In‐situ XAS Study of Catalytic N2O Decomposition Over CuO/CeO2 Catalysts

“…The relative amounts of Ce 4+ and Ce 3+ species in the catalyst before and during the catalytic reaction at 400 °C (Figure 5) were determined from the Ce L 3 ‐edge XANES spectra by the linear combination fit (LCF) analysis [29,38] . The spectra can be completely described by a linear combination of up to two components: Ce L 3 ‐edge XANES profile of the sample 4Cu_CeO 2 −R catalyst in initial state at RT as reference for Ce 4+ , and XANES of crystalline CeVO 4 as reference for Ce 3+ .…”

Strain‐Engineered Formation, Migration, and Electronic Properties of Polaronic Defects in CeO2

“…[12,[20][21][22][23] The polaronic effect, involving the strong coupling between charge and lattice vibrations, has recently attracted considerable attention among condensed matter and materials science communities. [12,24,25] A broad range of novel polaronic quantum phenomena have been demonstrated, such as colossal magnetoresistance, [26] anomalous photovoltaics, [27,28] and exciton dynamics. [29] It was reported that polaronic defects regulate the adsorption of gas molecules [30] and enhance chemical reactions (such as CO oxidation) [31] on the oxide surface.…”