Multiple scattering approach to the Pt L2-edge XANES of CO adsorption on small Pt particles

Notoya, Yasuharu; Hayakawa, Kuniko; Fujikawa, Takashi; Kubota, Takeshi; Shido, Takafumi; Asakura, Kiyotaka; Iwasawa, Yasuhiro

doi:10.1016/s0009-2614(02)00577-8

Cited by 6 publications

(3 citation statements)

References 16 publications

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“…Due to retrodonation of d electrons from Pt to the CO 2p* antibonding orbital, there is an increase in the d vacancies of Pt sites. 49 Thus, at this reduction temperature, the Pt6CeTi catalyst has a stronger affinity for CO adsorption, pointing out the improved Pt reducibility for this sample as seen previously by H 2 -TPR. After reduction at 300 1C, the XANES spectra of both samples are almost equivalent indicating that the generated metallic platinum has similar characteristics in both reduced PtCeTi catalysts.…”

Section: Catalysts Evolution During Reductionsupporting

confidence: 65%

In situ characterization of Ptcatalysts supported on ceria modified TiO2 for the WGS reaction: influence of ceria loading

Barrio¹,

Gong²,

González³

et al. 2012

Phys. Chem. Chem. Phys.

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This work analyzes the influence of cerium content (6-15 wt%) on a TiO(2) support over the structure and water gas shift (WGS) activity of Pt catalysts. The structural properties of these Pt/Ce-TiO(2) catalysts were characterized by XRD, TEM and XANES. Physicochemical characterization of the catalysts showed differences in the structure and dispersion of Ce entities on the support with Ce loading. For the samples with low ceria content (6 wt%), cerium is deposited on the support in the form of CeO(x) clusters in a highly dispersed state in close interaction with the Ti atoms. The formation of CeO(x) clusters at low Ce-loading on the support facilitates the dispersion of small particles of Pt and improves the reducibility of ceria component at low temperatures. The changes in platinum dispersion and support reducibility with Ce-loading on the TiO(2) support lead to significant differences in the WGS activity. Pt supported on the sample with lower Ce content (6 wt%) shows better activity than those corresponding to catalysts with higher Ce content (15 wt%). Activity measurements coupled with catalysts characterization suggest that the improvement in the reducibility of the support with lower Ce content was associated with the presence of CeO(x) clusters of high reducibility that improve the chemical activity of the oxide-metal interfaces at which the WGS reaction takes place.

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Section: Catalysts Evolution During Reductionsupporting

confidence: 65%

In situ characterization of Ptcatalysts supported on ceria modified TiO2 for the WGS reaction: influence of ceria loading

Barrio¹,

Gong²,

González³

et al. 2012

Phys. Chem. Chem. Phys.

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“…The spin–orbit interaction leads to large differences between the L 3 and L 2 absorption edges, and L 3 transitions are more favored by selection rules than L 2 transitions . However, many good examples can be found in the literature where the Pt L 2 -edge has produced the correct trends in the electronic structure. − …”

Section: Resultsmentioning

confidence: 99%

Impact of Transition Metal Carbide and Nitride Supports on the Electronic Structure of Thin Platinum Overlayers

et al. 2019

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Atomically thin platinum (Pt) shells on titanium tungsten carbide (TiWC) and titanium tungsten nitride (TiWN) core nanoparticles display substantially modified catalytic performance compared to commercial Pt nanoparticles. In situ X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses indicate these differences are primarily caused by ligand effects from the hybridization of Pt and W d states at the core−shell interface. The heterometallic bonding between the shell and the core elements leads to broadening of the Pt valence d-band, a downshift of the d-band center, and greatly reduced adsorbate binding energies, as verified by density functional theory calculations and microcalorimetry of CO adsorption. In situ XANES measurements during reduction treatment demonstrated how surface oxides disrupt the bonding interactions between Pt and W. Changes to the Pt electronic structure from different core materials correlated with ethylene hydrogenation reactivity, where increased Pt d-band broadening was associated with weaker adsorbate binding and consequently lower turnover frequency. The significant electronic structure modification of Pt by the TiWC and TiWN cores exemplifies how core−shell nanoparticle architectures can be used to tune catalyst reactivity.

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“…To date, we have analyzed XANES spectra for various disordered systems using of the short-range-order full multiple-scattering approach and have obtained detailed structural information. 17,18) Our main purpose of this study is to obtain some useful information on structural and electronic properties around bromine by XANES analyses. For that purpose, we apply the full multiple-scattering approach 19,20) to the observed Br K-edge XANES at various temperatures reported in ref.…”

Section: Introductionmentioning

confidence: 99%

Br K-Edge X-ray Absorption Near Edge Structure Analyses of Bromine Residue Carbon Compounds Using Full Multiple-Scattering Theory

Uno

Notoya

Fujikawa

et al. 2005

Jpn. J. Appl. Phys.

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A recent experimental result shows that Br K-edge X-ray absorption near edge structure (XANES) spectra for bromine residue compounds are sensitive to the heat treatment of host carbon compounds. In the present study we attempt to extract useful information on the geometric and electronic structures of these systems by applying a full multiple-scattering approach to XANES analyses. The residue compounds can be classified into three groups on the basis of XANES spectral features. Present detailed analyses provide us some useful information: Group 1, bromine residue compounds are prepared from host carbon compounds heat-treated at 2000–2800°C, where Br2 molecules exist in the interlayer space of graphite. The interlayer distance expands to about 7.8 Å around the Br2 molecules. For heat treatment at 1900°C, the observed spectra are well explained by the superposition of the spectrum for Group 1 and that for Group 2, with a ratio of 3:4. For Group 2 heat-treated at 1500–1750°C, the host carbon compounds includes Br- ions, but no information on the Br-–C correlation has been obtained. For Group 3 heat-treated at 1000°C, the host carbon compounds mainly includes HBr molecules parallel to small aromatic carbon molecules.

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Multiple scattering approach to the Pt L2-edge XANES of CO adsorption on small Pt particles

Cited by 6 publications

References 16 publications

In situ characterization of Ptcatalysts supported on ceria modified TiO2 for the WGS reaction: influence of ceria loading

In situ characterization of Ptcatalysts supported on ceria modified TiO2 for the WGS reaction: influence of ceria loading

Impact of Transition Metal Carbide and Nitride Supports on the Electronic Structure of Thin Platinum Overlayers

Br K-Edge X-ray Absorption Near Edge Structure Analyses of Bromine Residue Carbon Compounds Using Full Multiple-Scattering Theory

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