Near-ambient XPS characterization of interfacial copper species in ceria-supported copper catalysts

Monte, Manuel J.S.; Munuera, G.; Costa, Dominique; Conesa, J.C.; Martı́nez-Arias, A.

doi:10.1039/c5cp04354a

Cited by 82 publications

(49 citation statements)

References 53 publications

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“…As already observed, concerning the Ce oxidation state, all the samples contained Ce 4+ with a minor percentage of Ce 3+ ions, some of which due to X-ray beam induced reduction during the XPS analyses [30]. The O 1s region contained two contributions, one due to lattice oxygen with BE of 529.4 ± 0.3 eV, the other to hydroxyl species with BE of 531.8 ± 0.4 eV [48]. The binding energy of Y 3d 5/2 at 157.6 ± 0.2 eV was typical of Y 3+ .…”

Section: Sample Characterizationmentioning

confidence: 72%

Effect of Y Modified Ceria Support in Mono and Bimetallic Pd–Au Catalysts for Complete Benzene Oxidation

et al. 2018

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Mono metallic and bimetallic Pd (1 wt. %)-Au (3 wt. %) catalysts were prepared using two ceria supports doped with 1 wt. % Y 2 O 3 . Yttrium was added by impregnation or co-precipitation. The catalyst synthesis was carried out by deposition-precipitation method, with sequential deposition-precipitation of palladium over previously loaded gold in the case of the bimetallic samples. The obtained materials, characterized by X-ray powder diffraction (XRD), High resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and temperature programmed reduction (TPR) techniques, were tested in the complete benzene oxidation (CBO). The results of the characterization analyses and the catalytic performance pointed to a close relationship between structural, redox, and catalytic properties of mono and bimetallic catalysts. Among the monometallic systems, Pd catalysts were more active as compared to the corresponding Au catalysts. The bimetallic systems exhibited the best combustion activity. In particular, over Pd-Au supported on Y-impregnated ceria, 100% of benzene conversion towards total oxidation at the temperature of 150 • C was obtained. Comparison of surface sensitive XPS results of fresh and spent catalysts ascertained the redox character of the reaction.

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Section: Sample Characterizationmentioning

confidence: 72%

Effect of Y Modified Ceria Support in Mono and Bimetallic Pd–Au Catalysts for Complete Benzene Oxidation

et al. 2018

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“…Ambientpressure X-ray photoelectron spectroscopy (XPS) characterization, together with DFT calculations, verify that the lower reducibility of CuO particless upported on the {100} facets of CeO 2 nanocubes is due to extensive electron transfer from CuO to CeO 2 . [56] However,t his electronic interaction benefits the catalytic performance of Cu particles supportedb yC eO 2 nanocubes for the preferential oxidationo fC Oi nH 2 -rich streams. [53] The chemical potentialo ft he Cu atoms over step edges of the CeO 2 (111)s urface is approximately 57 kJ mol À1 lower than that on stoichiometrict errace sites, whichi mplies that the stability of the Cu nanoparticles and the Cu-CeO 2 interaction can be strongly influenced by the coordination environment of the CeO 2 surfaces.…”

Section: Cu/ceo 2 Catalystsmentioning

confidence: 99%

Shape Engineering of Oxide Nanoparticles for Heterogeneous Catalysis

Zhou

Shen

2016

Chemistry An Asian Journal

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The fabrication of oxide particles with tunable sizes and shapes at the nanoscale is one of the most crucial issues for the design and development of highly efficient heterogeneous catalysts. The shape of oxide nanoparticles has been demonstrated to affect their catalytic properties remarkably. Tuning the shape of oxide particles allows preferential exposure of specific reactive facets; this can maximize the number of active sites available to the reactants, which can improve the activity and also mediate the reaction route to a specific channel to achieve higher selectivity for a particular chemical reaction. In addition, the shape of the oxide particles affects their interaction with metal particles or clusters, and this involves interfacial strain and charge transfer. Metal particles or clusters dispersed on the reactive or polar facets of the oxide support often provide superior catalytic performance, primarily because of strong metal-support interactions. However, the geometric and electronic features of the metal-oxide interface may change during the course of the reaction, induced by chemisorption of reactive molecules at elevated temperatures, which should be taken into account in proposing a structure-reactivity relationship.

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“…Fewer -OH groups were detected after the pretreatment in air at 350˝C but they still exist; for ceria, the elimination of residual hydroxyls through thermal decomposition under air requires a relatively high temperature (above 600˝C [31]). In both fresh Au1YCeIM and Au1YCeCP catalysts, the at.…”

Section: Sample Characterizationmentioning

confidence: 99%

“…It means that there is enrichment by unreducible Y 3+ ions surrounded by oxygen vacancies which do not participate in the reoxidation process, resulting in the lack of oxygen supply. The spectra in the O 1s region could be separated in two contributions due to the lattice oxygen (a BE between 529.0 and 530.3 eV [31]) and hydroxyl species (except fresh Au1YCeCP with a supplemental small contribution of oxygen in the C-O-C bond). Fewer -OH groups were detected after the pretreatment in air at 350 °C but they still exist; for ceria, the elimination of residual hydroxyls through thermal decomposition under air requires a relatively high temperature (above 600 °C [31]).…”

Section: Sample Characterizationmentioning

confidence: 99%

“…Even in the A careful analysis of C 1s spectra revealed the coexistence of various carbon-like species at the surface of both measured fresh catalysts (see Table 3). However, it is not possible to discuss the presence of carbonates using the XPS spectra as it is known that the BE position of carbon in carbonate species (COOH) is within the range of 288.4 to 290 eV and it is overlapped with the broad Ce 4s peak of 289.4 to 289.7 eV [31][32][33]. It is interesting to note that the total amount of C in the less active Au1YCeCP catalyst used in CBO is considerably higher than in the corresponding Au1YCeIM sample (25.4 and 9.6 at.…”

Section: Sample Characterizationmentioning

confidence: 99%

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Gold Catalysts on Y-Doped Ceria Supports for Complete Benzene Oxidation

et al. 2016

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Gold (3 wt. %) catalysts on Y-doped (1, 2.5, 5 and 7.5 wt. % Y 2 O 3 ) ceria supports prepared by coprecipitation (CP) or impregnation (IM) were studied in complete benzene oxidation (CBO). A low-extent Y modification was chosen to avoid ordering of oxygen vacancies. The samples were characterized by XRD, TGA, XPS and TPR techniques. A positive role of air pretreatment at 350˝C as compared to 200˝C was established for all Y-containing catalysts and it was explained by cleaning the active sites from carbonates. The oxygen supply cannot be considered as a limiting step for benzene oxidation except for the high 7.5%-doped samples, as suggested by TGA and TPR data. On the basis of XPS results of fresh and used in CBO catalysts, the presence of cationic gold species does not seem important for high CBO activity. The gold catalyst on an IM support with 1% Y-doping exhibited the best performance. A 100% benzene conversion was achieved only over this catalyst and Au/ceria, while it was not reached even at 300˝C over all other studied catalysts. Gold and ceria particle agglomeration or coke formation should be excluded as a possible reason, and the most probable explanation could be associated with the importance of the benzene activation stage.

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Near-ambient XPS characterization of interfacial copper species in ceria-supported copper catalysts

Cited by 82 publications

References 53 publications

Effect of Y Modified Ceria Support in Mono and Bimetallic Pd–Au Catalysts for Complete Benzene Oxidation

Effect of Y Modified Ceria Support in Mono and Bimetallic Pd–Au Catalysts for Complete Benzene Oxidation

Shape Engineering of Oxide Nanoparticles for Heterogeneous Catalysis

Gold Catalysts on Y-Doped Ceria Supports for Complete Benzene Oxidation

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