XPS comparative study of ceria/zirconia mixed oxides: powders and thin film characterisation

Galtayries, Anouk; Sporken, R.; Riga, J.; Blanchard, G.; Caudano, R.

doi:10.1016/s0368-2048(97)00134-5

Cited by 206 publications

(127 citation statements)

References 15 publications

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“…The interpretation of the XPS spectrum of Ce3d ( Figure A1) is very complex with overlapped peaks, although a rather precise deconvolution can be made [30,31]. The spectra show two main signals at binding energies about 901 and 883 eV, which are assigned to Ce 3d3/2 and Ce 3d5/2, respectively.…”

Section: Resultsmentioning

confidence: 99%

Total Oxidation of Propane Using CeO2 and CuO-CeO2 Catalysts Prepared Using Templates of Different Nature

et al. 2017

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Several CeO 2 and CuO-CeO 2 catalysts were prepared using different methods, i.e., a homogeneous precipitation with urea, a nanocasting route using CMK-3 carbon as a hard template and a sol-gel process using Poly(methyl methacrylate) (PMMA) polymer as a soft template, and tested in the total oxidation of propane. The catalysts were characterized by a number of physicochemical techniques (XRD, N 2 adsorption, TPR, XPS, Raman spectroscopy) showing distinct characteristics. For each series, Cu-Ce-O catalysts with low Cu-loadings (5 wt % CuO) showed the highest activity, higher than those samples either without copper or with high Cu-loading (13 wt % CuO). The incorporation of copper leads to an increase of the concentration of bulk defects but if the Cu-loading is too high the surface area drastically falls. The highest activity in the total oxidation of propane was achieved by Cu-containing ceria catalysts synthesized using a polymer as a template, as this method yields high surface area materials. The surface area and the number of bulk/sub-surface defects of the ceria seem to be the main properties determining the catalytic activity.

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Section: Resultsmentioning

confidence: 99%

Total Oxidation of Propane Using CeO2 and CuO-CeO2 Catalysts Prepared Using Templates of Different Nature

et al. 2017

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“…It could be interpreted as similar mobilities of the lattice oxygen in the LSC and LSCC10, indicating an absence of obstructions for oxygen transport in the area directly adjacent to the phase interfaces and across the interface {modified perovskite/modified ceria}. In the LSCC57, the O 1s components at BE ∼ 528.2-528.6 eV was not revealed, but the peak at BE ∼ 529.4 eV was observed and can be assigned to the lattice oxygen in pure or doped CeO 2 [24,55] and to SrO species on the surface of perovskites [36]. The O 1s component at ∼530.6-530.8 eV (LSC, LSCC10, and LSCC37) could be associated with O-Co surface species in perovskites [36] and this component is strong for the LSC, LSCC10, and LSCC37 compositions.…”

Section: Surface States Of Co and Sr Cations Carbon And Oxygen Ionsmentioning

confidence: 92%

“…X-ray photoelectron spectroscopy (XPS) is the method that allows monitoring changes in the local environment of ions and their oxidations states [17]. The surface chemical states of Ce cations have been explored so far preferably for undoped CeO 2 [18][19][20][21][22][23], CeO 2 -based solid solutions [24][25][26], and composites composed of CeO 2 and transition metals or their oxides [27][28][29][30][31][32][33][34]. It was shown that properties of composite materials (redox properties, formation of surface and bulk oxygen vacancies, oxygen storage and release) can be optimised through the variation of the CeO 2 /Me(Me x O y ) ratios.…”

Section: Introductionmentioning

confidence: 99%

Identification of surface composition and chemical states in composites comprised of phases with fluorite and perovskite structures by X-ray photoelectron spectroscopy

Konysheva

Francis

2013

Applied Surface Science

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Keywords:X-ray photoelectron spectroscopy (XPS) Surface composition Composites with perovskite and fluorite structures Oxidation state of cerium cations Binding energy a b s t r a c t X-ray photoelectron spectroscopy (XPS) has been used to explore the cation rearrangement between the surface and bulk of grains and the surface chemical states of Ce, Mn, Co, Sr, and O ions in the single phase CeO 2 -based solid solutions and in the two phase (100 − x)La 0.6 Sr 0.4 CoO 3 -xCeO 2 (LSCCx) and (100 − x)La 0.8 Sr 0.2 MnO 3 -xCeO 2 (LSMCx) composites. The well-resolved Ce 3d 5/2 and Ce 3d 3/2 spin-orbit components were determined to study the Ce 4+ to Ce 3+ electronic transition at the surface. The surface of the LSCCx and LSMCx (x = 8-40 mol%) composites is depleted in cerium. Both Ce 4+ and Ce 3+ cations were revealed. The surface fraction of Ce 4+ cations increases with the rise in CeO 2 content in both systems, but it is higher by about a factor of two in the LSCC composites. A strong enrichment of the surface by Co cations was observed for the composites LSCCx (x = 8-40 mol%), implying that the presence of cerium could facilitate the Co surface segregation. A slight Sr surface enrichment compared to the nominal stoichiometry was found for La 0.6 Sr 0.4 CoO 3 , CeO 2 -based solid solutions, LSCC57, and LSMCx (x = 10-57) composites. In contrast, the surface of the LSCCx (x = 10-37) composites is slightly depleted in strontium cations. The O 1s spectra of the LSCC and LSMC composites contain several contributions associated with the lattice oxygen related to the phases with the perovskite and fluorite structures as well as with different surface states. Their contributions vary with CeO 2 content and a chemical origin of the transition metal cations on the B-site in the perovskite structure. The Ce 2 (CO 3 ) 3 -based phase seems to exist at the surface of grains and crystallites in the LSCC57 and LSCM composites.

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“…While the analysis of the XPS spectra of Ce 3d is very complex due to the presence of several overlapping peaks, a reasonably accurate deconvolution of the peaks can be made following previously reported methods. 50,51 The Ce 3d XPS spectra for Au-Pd/Ce-NR and Au-Pd/CeO 2 are presented in 15 The concentration of Ce 3+ in the ceria supports and catalysts was determined from the deconvoluted XPS spectra, and is given in Table S2 † and Table 2, respectively. The assynthesised ceria nanorods displayed a higher concentration of Ce 3+ (31%) in comparison with the ceria nanopowder (27%).…”

mentioning

confidence: 99%

Au–Pd NPs immobilised on nanostructured ceria and titania: impact of support morphology on the catalytic activity for selective oxidation

Khawaji

Chadwick

2018

Catal. Sci. Technol.

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Bimetallic Au-Pd nanoparticles supported on different ceria and titania nanostructures have been prepared by sol-immobilisation, and evaluated in the solvent-less selective oxidation of benzyl alcohol. The catalysts were characterised by TEM, STEM, XRD, XPS, ICP-AES, and nitrogen adsorption-desorption measurements.The activity of the catalysts was found to be strongly related to the morphology, structure and physiochemical properties of the supports. Au-Pd/ceria nanorods exhibited remarkably high catalytic activity (TOF > 35 900 h −1 ), and was found to be considerably more active than Au-Pd/titanate nanotubes, and Au-Pd catalysts supported on conventional ceria and titania nanopowders. The outstanding catalytic performance of Au-Pd/ceria nanorods is attributed to the unique surface chemistry of ceria nanorods, and the ability of catalyst preparation method (i.e. sol-immobilisation) to control the metal particle size and the bimetallic alloy formation. The presence of surface defects and high concentration of oxygen vacancies and Ce 3+ in ceria nanorods is likely responsible for the stabilisation of Au-Pd NPs during sol-immobilisation, which led to a very small mean particle size (2.1 nm) corresponding to a dispersion of approximately 52%, and a high surface metal concentration.

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XPS comparative study of ceria/zirconia mixed oxides: powders and thin film characterisation

Cited by 206 publications

References 15 publications

Total Oxidation of Propane Using CeO2 and CuO-CeO2 Catalysts Prepared Using Templates of Different Nature

Total Oxidation of Propane Using CeO2 and CuO-CeO2 Catalysts Prepared Using Templates of Different Nature

Identification of surface composition and chemical states in composites comprised of phases with fluorite and perovskite structures by X-ray photoelectron spectroscopy

Au–Pd NPs immobilised on nanostructured ceria and titania: impact of support morphology on the catalytic activity for selective oxidation

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