Ceria-samarium binary metal oxides: A comparative approach towards structural properties and soot oxidation activity

Anantharaman, Anjana P.; Geethu, J. S.; P, Mohammed Rishab; Dasari, Hari Prasad; Lee, Jong Ho; Dasari, Harshini; Babu, G. Uday Bhaskar

doi:10.1016/j.mcat.2018.01.033

Cited by 12 publications

(7 citation statements)

References 35 publications

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“…It is evident that the T 50 temperatures of doped samples are lower than C due to the improved lattice strain and (200) planes as studied from XRD. Amongst the smaller ionic radius samples (CT, CH, and CZ), CT has significantly lower activity (T 50 = 450°C) due to secondary phase formation as evident from XRD peaks which hinders the active site contact as reported earlier . Almost similar T 50 temperature obtained for CH and CZ (430°C and 425°C, respectively) could be due to the similar dopant ionic radius with the same oxidation state of 4+.…”

Section: Resultssupporting

confidence: 57%

Effect of ionic radius on soot oxidation activity for ceria‐based binary metal oxides

Anantharaman

Dasari

et al. 2019

Asia-Pacific J Chem Eng

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CeO2 (C) along with binary metal oxides of Ce0.9M0.1O2‐δ (M = Sn, Hf, Zr, Gd, Sm, and La; CT, CH, CZ CG, CS, and CL) are synthesized using the EDTA–citrate method. Samples having an ionic radius smaller (CT, CH, and CZ) and larger (CG, CS, and CL) than Ce4+ are classified separately, and their soot oxidation activity is analyzed. The incorporation of dopant is confirmed from lattice constant variation in X‐ray diffraction result. The critical descriptors for the activity are dopant nature (ionic radius and oxidation‐state), single‐phase solid solution, lattice strain, reactive (200) and (220) planes, Raman intensity ration (Iov/IF2g), optical bandgap, reducibility ratio, and surface oxygen vacancy. Smaller ionic radius, isovalent dopants (CH and CZ) create a defect site by lowering the optical bandgap along with improved surface oxygen vacancy concentration and thus enhanced soot oxidation activity. Aliovalent dopant with larger ionic radius shows the involvement of lattice oxygen in oxidation reaction by charge compensation mechanism. CL showed the highest activity amongst larger ionic radius samples.

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Section: Resultssupporting

confidence: 57%

Effect of ionic radius on soot oxidation activity for ceria‐based binary metal oxides

Anantharaman

Dasari

et al. 2019

Asia-Pacific J Chem Eng

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“…As shown in Figure b, crystallite sizes initially get larger with slight Sm 3+ doping but dwindle to 10 nm as the doping concentration becomes heavy and later grow up to 31 nm while Sm 3+ takes over as the predominant lanthanide in Sm x Ce 1– x O 2−δ . It was reported that heavy Sm 3+ doping would break down the pristine lattice ordering of CeO 2 and impede the crystal growth by the reduction in valency and formation of Ce–O–Sm bond and V O . The preparation process, as discussed above, also plays a part in determining the size of Sm x Ce 1– x O 2−δ nanocrystals.…”

Section: Results and Discussionmentioning

confidence: 98%

Finely Tuned Structure and Catalytic Performance of Cerium Oxides by a Continuous Samarium Doping from 0 to 100%

Tao

Zhong

et al. 2019

Inorg. Chem.

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Cerium oxides are prevalent catalytic materials, and the lanthanide-doped ceria have attracted special interest since it is easy to tune the concentration of oxygen vacancies (VO) by changing the doping content. The presence of VO is generally believed to favor a catalytic reaction, but the formation of dopant-vacancy associations at a high doping concentration might produce an adverse effect. Herein, evolutions of the structural properties and catalytic performances in Sm-doped ceria (Sm x Ce1–x O2−δ, x = 0–1) are investigated to explore the doping effect of Sm3+ on the ceria-based nanoctrystals. The Sm x Ce1–x O2−δ films composed of nanoctrystals are elaborately prepared via electrodeposition under mild conditions to prevent phase separation. A combination of studies, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, photoluminescence (PL), and methanol electro-oxidation (MEO) reaction, reveals that variation trends for the VO concentration and catalytic property of Sm x Ce1–x O2−δ are unsynchronized. The lattice structures of Sm x Ce1–x O2−δ nanoctrystals undergo a smooth and steady transition from F-type (fluorite CeO2) to C-type (cubic Sm2O3) with the increase of Sm3+ contents. The structural transition occurs in the Sm3+ concentration range of 64–84%, within which the VO concentration reaches the maximum as well. However, the optimal MEO performance is obtained at a relatively lower doping concentration of 24%. Above this concentration, significant dopant-vacancy associates are observed by XRD, Raman, and PL characterizations. It is inferred that, for these ceria-based nanocrystals, the dopant-vacancy association induced by high doping would impede the growth of catalytic performance despite all the benefits of VO.

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“…1a. The diffraction peaks correspond to the planes [(111), ( 200), (220), (311), ( 222), (400), (331), and (422)] of fluorite structure of CeO 2 for all Nb-doped ceria and pure CeO 2 samples [37,59]. The dominant diffraction peaks for planes [(001), (100), ( 101), (002), ( 110), ( 102), (201), and (112)] correspond to pure Nb samples.…”

Section: Resultsmentioning

confidence: 99%

“…CeO 2 when doped with rare earth materials and lanthanides such as praseodymium (Pr) [33][34][35], lanthanum (La) [2], gadolinium (Gd) [35,36], samarium (Sm) [19,37], and neodymium (Nd) [21] provided excellent performance for soot oxidation activity. It showed an evident reduction in temperature required for oxidation of soot when compared to undoped/ pure CeO 2 and bare soot [33].…”

Section: Introductionmentioning

confidence: 99%

A Negative Effect of Niobium‐Doped Ceria on Soot Oxidation Activity^‡

et al. 2022

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Niobium-doped ceria catalysts were synthesized to study soot oxidation activity. X-Ray diffraction (XRD) and Raman analysis of the samples revealed the presence of a fluorite structure of CeO 2 for all the doped samples. The T 50 temperature of the pure CeO 2 sample was more significant than that of bare soot. The high catalytic activity of the CeO 2 catalyst can be attributed to the low crystallite size, high facet ratio, and the large Brunauer-Emmett-Teller (BET) surface area as compared to Nb-doped samples. The activation energy calculated by both Ozawa and KAS methods were found to be low for CeO 2 when compared to Nb-doped samples. CeO 2 resulted in better soot oxidation activity with low activation energy.

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Ceria-samarium binary metal oxides: A comparative approach towards structural properties and soot oxidation activity

Cited by 12 publications

References 35 publications

Effect of ionic radius on soot oxidation activity for ceria‐based binary metal oxides

Effect of ionic radius on soot oxidation activity for ceria‐based binary metal oxides

Finely Tuned Structure and Catalytic Performance of Cerium Oxides by a Continuous Samarium Doping from 0 to 100%

A Negative Effect of Niobium‐Doped Ceria on Soot Oxidation Activity^‡

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Ceria-samarium binary metal oxides: A comparative approach towards structural properties and soot oxidation activity

Cited by 12 publications

References 35 publications

Effect of ionic radius on soot oxidation activity for ceria‐based binary metal oxides

Effect of ionic radius on soot oxidation activity for ceria‐based binary metal oxides

Finely Tuned Structure and Catalytic Performance of Cerium Oxides by a Continuous Samarium Doping from 0 to 100%

A Negative Effect of Niobium‐Doped Ceria on Soot Oxidation Activity‡

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A Negative Effect of Niobium‐Doped Ceria on Soot Oxidation Activity^‡