“…Generally, the catalytic activity of nanoceria is directly related to its surface chemical states and specific surface area 11 . The high concentration of Ce 3+ facilitates the adsorption and decomposition of H 2 O 2 4,5,42 . Hence, the high activity of nanorods was owing to the presence of more Ce 3+ , as proved by XPS analysis.Figure 3H 2 O 2 decomposition over CeO 2 nanorods and nanocubes (1.0 g L −1 CeO 2 , 20 mM H 2 O 2 , 25 °C).…”
The Fenton-like activity of nanoceria has attracted intensive attention for wastewater treatment in recent years. During the Fenton-like reaction, the adsorption of organic pollutants on catalyst surface plays a key role in their degradation. In this work, the adsorption-degradation of methylene blue (MB) and Congo red (CR) in nanoceria/H2O2 system was investigated under alkaline conditions. The MB exhibited weak adsorption on nanoceria surface via electrostatic attraction, while strong Lewis acid–base interactions between CR and cerium ions was observed. Moreover, the adsorption of MB was enhanced in the presence of H2O2 by the formation of surface peroxide species, but an adsorption competition existed between H2O2 and CR. With more Ce3+, CeO2 nanorods could degrade CR efficiently as Fenton-like catalyst. But the degradation of MB catalyzed by ceria was much lower than that of CR in the presence of H2O2.
“…Generally, the catalytic activity of nanoceria is directly related to its surface chemical states and specific surface area 11 . The high concentration of Ce 3+ facilitates the adsorption and decomposition of H 2 O 2 4,5,42 . Hence, the high activity of nanorods was owing to the presence of more Ce 3+ , as proved by XPS analysis.Figure 3H 2 O 2 decomposition over CeO 2 nanorods and nanocubes (1.0 g L −1 CeO 2 , 20 mM H 2 O 2 , 25 °C).…”
The Fenton-like activity of nanoceria has attracted intensive attention for wastewater treatment in recent years. During the Fenton-like reaction, the adsorption of organic pollutants on catalyst surface plays a key role in their degradation. In this work, the adsorption-degradation of methylene blue (MB) and Congo red (CR) in nanoceria/H2O2 system was investigated under alkaline conditions. The MB exhibited weak adsorption on nanoceria surface via electrostatic attraction, while strong Lewis acid–base interactions between CR and cerium ions was observed. Moreover, the adsorption of MB was enhanced in the presence of H2O2 by the formation of surface peroxide species, but an adsorption competition existed between H2O2 and CR. With more Ce3+, CeO2 nanorods could degrade CR efficiently as Fenton-like catalyst. But the degradation of MB catalyzed by ceria was much lower than that of CR in the presence of H2O2.
“…In particular, Pr and Fe codoped CeO 2 (PFC9) showed the highest Ce 3+ ratio of 20.6%, suggesting that the introduction of trivalent Fe 3+ and Pr 3+ species into CeO 2 causes the partial reduction of the Ce tetravalent cation. Because the formation of Ce 3+ accompanied the formation of oxygen vacancy in the sample, the results herein corroborate the oxygen vacancy evaluation in Fig. (a).…”
Section: Resultsmentioning
confidence: 99%
“…For the Pr and Fe codoped CeO 2 (PFC9, Ce 0.982 Pr 0.003 Fe 0.015 O 2‐σ ), the dopant band generated by Pr 3+ , Fe 3+ and Ce 3+ (accompanied by oxygen vacancy) of ceria are located below the conduction band in ceria . Based on the above‐determined results of active species and the energy band positions, a possible mechanism for the high photocatalytic activity of the PFC9 is proposed in Fig.…”
Section: Resultsmentioning
confidence: 99%
“…17 Doping rare earth ions is another simple and effective strategy to modify the energy band of semiconductor oxides and the defects of the crystals. [18][19][20][21] Among the rare earth ions, the radii of praseodymium (Pr) ions is slightly smaller than those of Ce ions (Ce 4+ = 1.110 Å; Ce 3+ = 1.283 Å; Pr 4+ = 1.100 Å; Pr 3+ = 1.266 Å). 19 Therefore, Pr ions can enter the crystal lattice of CeO 2 , but will not induce a severe crystal lattice deformation like Fe.…”
“…It can be inferred that oxygen vacancies are generated in the samples, because the Ce 4+ cation is replaced by ions with a lower valence state, as in the case of Pr 3+ . Equation represents this phenomenon.where represents oxygen vacancies.…”
Nanoparticles of Ce 1−x Pr x O 2 (X: 0.6 and 0.8), were synthesized by the combustion method using citric acid as chelating and fuel agent. The X-ray diffraction patterns and Rietveld refinements confirm that samples shown as a single phase in a cubic fluorite structure, with an increase in the lattice parameter as a function of Pr concentration. The crystallite size domains obtained by the Scherrer formula, confirm values around 10 and 37 nm. The scanning electron microscopy images, show that the solids are composed of dense heterogeneous aggregates. The X-ray photoelectron spectroscopy, reveals that oxides are composed of cerium and praseodymium cations in oxidation states 4+ and 3+ respectively. The TPR-H 2 profiles indicate that cerium and praseodymium cations present in the obtained systems are completely reduced to Ce 3+ and Pr 3+ at temperatures above 790°C. The impedance spectroscopy data at room temperature showed that the conduction processes for the two systems take place at the grain boundaries. The Ce 0.2 Pr 0.8 O 2 system offer lower resistance, due to the high amount of Pr 3+ ions inserted in the structure and the high amount of oxygen vacancies formed in the synthesis process.
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