Spectroscopic studies of the structural properties of Ni substituted spinel LiMn2O4

Wei, Yingjin; Nam, Kyung‐Wan; Kim, Kwang Bum; Chen, Gang

doi:10.1016/j.ssi.2005.10.015

Cited by 62 publications

(32 citation statements)

References 34 publications

(28 reference statements)

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“…This peak is assigned to the F 2g phonon mode of cubic fluorite CeO 2 [40,41]. This band was also detected in the Raman spectra for the ceria-supported cobalt spinel catalysts with the [42,43,44]. The position of the F 2g peak of the ceria support does not change upon deposition of the cobalt oxide phase regardless the Co loading, implying that cobalt do not form a solid solution with ceria, in contrast to previous claims [45].…”

Section: Elemental and Structural Characterizationmentioning

confidence: 67%

Strong dispersion effect of cobalt spinel active phase spread over ceria for catalytic N2O decomposition: The role of the interface periphery

Grzybek

Stelmachowski

Gudyka

et al. 2016

Applied Catalysis B: Environmental

105

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dispersion effect of cobalt spinel active phase spread over ceria for catalytic N2O decomposition: the role of the interface periphery, Applied Catalysis B, Environmental http://dx.doi.org/10. 1016/j.apcatb.2015.07.027 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The catalytic tests in deN 2 O reaction revealed that the 10 wt.% of cobalt spinel in supported system is able to reproduce the activity of bare Co 3 O 4 catalyst. However, it was found that the catalyst with the lowest content of Co 3 O 4 equal to 1 wt.% exhibits the highest apparent reaction rate per mass of the spinel active phase. The observed activity was explained basing on the transmission electron microscopy analysis in terms of the dispersion of spinel phase over ceria support. A simple model that accounts for the observed strong dispersion effect is proposed. It consists in a two-step mechanism, where N 2 O is dissociated on the spinel nanograins and the resultant oxygen species are preferentially recombined at the Co 3 O 4 /CeO 2 interface periphery.

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Section: Elemental and Structural Characterizationmentioning

confidence: 67%

Strong dispersion effect of cobalt spinel active phase spread over ceria for catalytic N2O decomposition: The role of the interface periphery

Grzybek

Stelmachowski

Gudyka

et al. 2016

Applied Catalysis B: Environmental

105

View full text Add to dashboard Cite

show abstract

“…Five characteristic Raman peaks presented in the Fig. 2 correspond to the E g , 3F 2g and A 1g vibration modes of the crystalline Co 3 O 4 (m 1 = 198 (F 2g ), m 2 = 486 (E g ), m 3 = 525 (F 2g ), m 4 = 624 (F 2g ), m 5 = 695 cm -1 (A 1g )), as discussed in more detail elsewhere [44,45]. The structural changes of the spinel structure would manifest in an increased asymmetry of the A 1g band as evidenced for Mg and Al substituted Co 3 O 4 [28].…”

Section: Resultsmentioning

confidence: 92%

The Effect of the Preparation Method of Pd-Doped Cobalt Spinel on the Catalytic Activity in Methane Oxidation Under Lean Fuel Conditions

et al. 2016

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In this work a series of cobalt spinel catalysts was synthesized by different methods and doped with 1 wt% of palladium via incipient wetness impregnation or solution combustion synthesis (SCS). Both undoped and Pd-doped spinels were characterized from the structural and surface point of view (XRD, XRF, lRS, BET, FESEM) and tested toward the oxidation of methane in lean conditions, in gas mixtures containing from 0.5 to 2 vol% of CH 4 . These methane concentrations are typical of processes involving combustion of CH 4 in lean conditions as the after-treatment of unconverted CH 4 in compressed natural gas-fed vehicle exhausts, or the treatment of fugitive CH 4 from leaks in coal mines. The temperature window for the catalytic activity of the undoped Co 3 O 4 materials spread from 350 to 600°C. The preparation method affected the catalytic activity of undoped Co 3 O 4 , with the best catalytic activity related to the spinel prepared by SCS employing urea. The addition of 1 wt% of Pd lowered the temperature window for the catalytic activity to the range of 250-500°C, with insignificant differences for the various preparation methods. The beneficial effect of Pd-doping was assigned to the enhancement of the reduction of cobalt in the oxide structure.

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“…However, the measured Raman spectra of LiMn 2 O 4 differed [12,19−21] in the total amount of Raman bands, band positions, relative intensities, and full-width at half maximum (FWHM) of the corresponding Raman bands. Wei et al [19] prepared the spinel LiMn 2 O 4 sample using the molten salt method at 700…”

mentioning

confidence: 99%

“…The band at 626 cm −1 can be assigned to the symmetric Mn-O stretching vibration of the MnO 6 groups for the A 1g symmetry in the O 7 h space group [20,21] . Its broadening may be attributed to the slightly different structures between the isotropic Mn 4+ O 6 octahedra and the locally distorted Mn 3+ O 6 octahedra in spinel LiMn 2 O 4 [19,21] . The shoulder at 584 cm −1 can be assigned to the F concentration in the material and reflects the Mn average oxidation state [19,21] .…”

mentioning

confidence: 99%

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Raman spectroscopy study of in situ change in laser irradiated LiMn2O4

Liu

Han

2012

中国光学快报

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A spinel LiMn2O4 is investigated via Raman spectroscopy at 514.5-nm excitation and X-ray diffraction. The dependence of Raman spectra on the different irradiated laser powers is determined and found to be different from that at 632.8-nm excitation. Based on our extensive analysis, our experimental results can be attributed to the laser heating effect, which reduces the Mn 4+ cation concentration in the local area. Consequently, the decrease in average Mn valence in the local area unavoidably induces the Jahn-Teller effect and local lattice distortion, which accounts for the evolution of the measured Raman spectra of spinel LiMn2O4.

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Spectroscopic studies of the structural properties of Ni substituted spinel LiMn2O4

Cited by 62 publications

References 34 publications

Strong dispersion effect of cobalt spinel active phase spread over ceria for catalytic N2O decomposition: The role of the interface periphery

Strong dispersion effect of cobalt spinel active phase spread over ceria for catalytic N2O decomposition: The role of the interface periphery

The Effect of the Preparation Method of Pd-Doped Cobalt Spinel on the Catalytic Activity in Methane Oxidation Under Lean Fuel Conditions

Raman spectroscopy study of in situ change in laser irradiated LiMn2O4

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