Photoelectron spectroscopy of ceria: Reduction, quantification and the myth of the vacancy peak in XPS analysis

Abstract

Primarily due to its inherent redox chemistry, ceria (CeO2) is of use in many diverse areas of research. However, there is a wealth of misinterpretation of the oxygen spectra when discussing the result of damage or reduction to the CeO2 lattice, especially with regard to a signal in this region attributed to oxygen vacancies. In this paper, it is shown that this peak cannot be due to vacancies and that a better understanding of the changes in stoichiometry of CeO2 is best viewed from that of the Ce(III) component when considered in tandem with the O 1s signal.

Cr-Doped CeO2 Nanocrystals Supported on Reduced Graphene Oxide Nanosheets for Electrocatalytic Hydrogen Evolution

“…The elemental composition and chemical states of CeG, 5CrCeG, and 10CrCeG were analyzed via XPS, aiming to unravel the underlying processes contributing to the improved HER performance stemming from the structural modifications within the Cr-CeO 2 /rGO nanocomposites, as depicted in Figure . In Figure a–c, the Ce 3d orbitals revealed 10 peaks, constituting two sets of spin orbits: the 3d 3/2 orbitals comprising five peaks (designated as u‴ , u″ , u’ , u , and u o ) and the 3d 5/2 orbital encompassing another five peaks (designated as v‴ , v″ , v’ , v , and v o ). , Notably, v , v o , u , and u o corresponded to the characteristic peaks associated with Ce 3+ species. After scrutinizing these peaks, the Ce 3+ ratio was found to be 34.3% for the CeG sample.…”

“…In Figure 4a−c, the Ce 3d orbitals revealed 10 peaks, constituting two sets of spin orbits: the 3d 3/2 orbitals comprising five peaks (designated as u‴, u″, u', u, and u o ) and the 3d 5/2 orbital encompassing another five peaks (designated as v‴, v″, v', v, and v o ). 47,48 Notably, v, v o , u, and u o corresponded to the characteristic peaks associated with Ce 3+ species. After scrutinizing these peaks, the Ce 3+ ratio was found to be 34.3% for the CeG sample.…”

Highly Stable Pt/CeO2 Catalyst with Embedding Structure toward Water–Gas Shift Reaction

“…Additionally, XPS spectra of O 1 s can be fitted to three peaks at ∼529.5, ∼531.5, and ∼533.0 eV, which are assigned to the lattice oxygen (O 2– ), surface hydroxyl, and weakly adsorbed water, respectively (Figure S23c). − Figure S23d depicts that the proportions of Pt δ + and O v –Ce 3+ in Pt/CeO 2 (110) are larger than those in Pt/CeO 2 (100), indicating an enhanced strength of metal–support interaction in the former case. TOF values are calculated at a low CO conversion (<15%) (Table S3), and Pt/CeO 2 (110) presents higher TOF value and Pt δ + –O v –Ce 3+ interfacial sites (Figures S25 and S26) than Pt/CeO 2 (100).…”

Facile Estimation of Surface Oxygen Vacancies in Co3O4 Catalysts with a Colorimetric Method

“…For one XPS experiment, the nanoparticle powder needs to be exposed to an ultrahigh vacuum (ca. 5.0 × 10 –9 mbar) inside the analysis chamber, and it usually takes about 10 h for obtaining an ultrahigh vacuum . In this TMB-H 2 O 2 -Fe 2 O 3 colorimetric experiment, the reaction took less than 20 min.…”

“…5.0 × 10 −9 mbar) inside the analysis chamber, 51 and it usually takes about 10 h for obtaining an ultrahigh vacuum. 52 In this TMB-H 2 O 2 -Fe 2 O 3 colorimetric experiment, the reaction took less than 20 min. Then, the efficiency of the colorimetric method is much higher than that of the XPS method.…”