Correlations between Oxygen Uptake and Vacancy Concentration in Pr-Doped CeO₂

Abstract

The oxygen uptake of a series of Pr–CeO 2 materials was measured using thermogravimetric analysis at 420 and 600 °C, and at both temperatures, 20% Pr–CeO 2 was found to have the highest uptake. The materials were characterized using X-ray diffraction and scanning transmission electron microscopy. Defects in the materials were identified using Raman spectroscopy, and ultraviolet–visible spectroscopy was used to show the presence of Pr cations in the +3 oxidation state. The existence of these species was attributed to be responsible for the ability of the materials to uptake oxygen. Electron energy loss spectroscopy was used to investigate the effect of Pr addition to CeO 2 ; the Ce M 5 /M 4 and O I B / I C ratios were calculated to indicate the relative changes in the Ce 3+ and oxygen vacancy concentration, respectively. There was no observable increase in the Ce 3+ concentration; however, the oxygen vacancy concentration increased with an increase in the Pr content. Thus, Pr increases the defect concentration and the ability of the materials to uptake oxygen.

Comparison of Enhanced Photocatalytic Degradation Efficiency and Toxicity Evaluations of CeO2 Nanoparticles Synthesized Through Double-Modulation

“…To confirm this, the O K -edge spectra of the CeO 2 NPs were compared and a large change was observed among the three different CeO 2 NPs unlike the XRD and Raman measurements, which had no structural change. Due to the large overlap of the O 2 p and Ce 4 f wave functions, the pre-edge peak (peak A) at the O K -edge yields the density of Ce 4 f states in CeO 2 NPs [ 39 , 40 , 41 ]. In other words, the O K -edge spectra ( Figure 1 c) confirmed that the intensity of peak A for the Cr@CeO x and Fe@CeO x NPs was smaller than that for bare CeO 2 NPs.…”

Copper- and Cobalt-Codoped CeO2 Nanospheres with Abundant Oxygen Vacancies as Highly Efficient Electrocatalysts for Dual-Mode Electrochemical Sensing of MicroRNA

“…As shown in Figure 2K, the Ce M 5,4 EELS spectra of CuCo−CeO 2 and CeO 2 show the presence of two Ce white lines, which are located at 884 and 902 eV because of the 3d 5/2 → 4f 7/2 (M 5 ) and 3d 3/2 → 4f 5/2 (M 4 ) electron transitions, respectively. 30 The chemical shift of the Ce M 5, 4 white lines and the relative-intensity ratio of these lines can be used to evaluate the redox properties of the CeO 2 samples. 10,31 Particularly, a higher intensity ratio of M 5 and M 4 peaks (IM 5 / IM 4 ) indicates a higher reducible nature.…”

“…Moreover, EELS experiments were also conducted to further investigate the valences of cerium ions on the CeO 2 surface. As shown in Figure K, the Ce M 5,4 EELS spectra of CuCo–CeO 2 and CeO 2 show the presence of two Ce white lines, which are located at 884 and 902 eV because of the 3d 5/2 → 4f 7/2 (M 5 ) and 3d 3/2 → 4f 5/2 (M 4 ) electron transitions, respectively . The chemical shift of the Ce M 5, 4 white lines and the relative-intensity ratio of these lines can be used to evaluate the redox properties of the CeO 2 samples. , Particularly, a higher intensity ratio of M 5 and M 4 peaks (IM 5 /IM 4 ) indicates a higher reducible nature. , According to the calculation results, the IM 5 /IM 4 ratio of CuCo–CeO 2 (0.8295) is higher than that of pure CeO 2 (0.7972), which indicates more Ce 3+ ions and a higher density of oxygen vacancies on the CeO 2 surface from the introduction of the Cu and Co dopants.…”

Structures, Phase Fields, and Mixed Protonic–Electronic Conductivity of Ba-Deficient, Pr-Substituted BaZr0.7Ce0.2Y0.1O3−δ

“…The Rietveld refinements were repeated on the basis of a multiple-cation partitioning (Table , column 4), leading to further improvement in the refinement quality criteria (blue symbols, Figure ). Cerium partitioning over the A and B perovskite sites was discounted on the basis of the higher energy required for the reduction of Ce 4+ to Ce 3+ as contrasted with the reduction of Pr 4+ to Pr 3+ …”