ESCA study of sputtered platinum films

Bancroft, G.M.; Adams, I.; Coatsworth, L. L.; Bennewitz, C. D.; Brown, J. D.; Westwood, W. D.

doi:10.1021/ac60353a050

Cited by 269 publications

(144 citation statements)

References 12 publications

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“…Figure 2 contains the XPS spectra of several different coverages of Pt grown on Au using the SLRR method. Two species [20]. With increasing Pt coverage, the amount of Pt 4? and Pt 2?…”

Section: Discussion 1: Film Characterizationmentioning

confidence: 99%

Near Surface Phase Transition of Solute Derived Pt Monolayers

et al. 2013

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As the loadings of precious metals in surfacechemical systems continue to decrease for photo-and electro-catalysts for energy and environmental applications, the study of near-surface electronic and atomic structure in functional materials becomes critically important. Extremely small quantities of active elements, whether grown as clusters or ultrathin films, exhibit changes in catalytic activity that arise from both size effects and electron-transfer effects. These size and transfer effects can be related to increased propensity for oxidation of the metallic deposit, as well as to various changes in electrochemical performance such as durability or required overpotential for a given reaction. This work establishes a minimum threshold for Pt loading beyond which bulk-type electronic behavior may be expected. By iteratively growing atomic monolayers and multilayers using selflimited electrodeposition and studying these films using core-electron spectroscopy (X-ray absorption and X-ray photoelectron spectroscopy), electrochemical methods and DFT-based computations the fundamental interactions that govern oxidation state and electron transfer near the surface of a Pt-Au bimetallic system have been explored. It has been shown that the Pt-Au system exhibits increased tendency for the Pt layer to remain cationic below a minimum threshold film thickness of two monolayers. At monodispersed levels of submonolayer coverage Pt exhibits deviated electronic structure, reactivity, and metal stability compared to films in excess of this minimum threshold thickness. At three monolayers Pt is thick enough to avoid the preference for cationicity and the resulting higher rates of metal dissolution, but thin enough to benefit from electron transfers from Au that assist in lowering the overpotentials for CO oxidation. This study shows the efficacy of a concerted method for the investigation of near-surface phenomena in multicomponent systems. By combining electrochemical and vacuum studies of solutederived samples with advanced computational techniques, a multifaceted understanding of these architectures has been achieved.

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“…Figure 2 contains the XPS spectra of several different coverages of Pt grown on Au using the SLRR method. Two species [20]. With increasing Pt coverage, the amount of Pt 4? and Pt 2?…”

Section: Discussion 1: Film Characterizationmentioning

confidence: 99%

Near Surface Phase Transition of Solute Derived Pt Monolayers

et al. 2013

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“…The position of the C 1s peak, that is, 284.4 eV was used to correct the binding energies for all catalysts for the small but observed charging effects. The spectra were deconvoluted using the peak half widths and area ratios for the spin orbit splitting peaks described in the literature [18][19][20][21]. The O 1s spectra of the different catalysts and the blank (untreated and catalyst free) carbon black support was also analysed suggesting the presence of AC@O groups (peak at 532.1 ± 0.15 eV) [18] and higher oxidized groups (538.6 ± 0.1 eV) on the carbon support.…”

Section: Xrd Characterizationmentioning

confidence: 99%

The role of the WO_xad-component to Pt and PtRu catalysts in the electrochemical CH₃OH oxidation reaction

Yang

Bock

MacDougall

et al. 2004

Journal of Applied Electrochemistry

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High surface area carbon-supported platinum-based catalysts, Pt/C, PtWO x /C, PtRu/C and PtRuWO x /C, were prepared via a chemical reduction route using single metal precursor salts. The catalyst particles were found to be in the nanoscale range, and the addition of Ru clearly decreased the particle size. The Ru was found to be partially incorporated into the face centered cubic lattice of Pt and to form a single Ru catalyst component. X-ray diffraction and X-ray photon spectroscopy did not provide evidence for electronic interactions between WO x and Pt as well as WO x and Ru. However, the addition of tungsten to the PtRuWO x /C catalyst resulted in a high degree of catalyst particle agglomeration. Both Ru containing catalysts showed significantly higher activities for the CH 3 OH oxidation reaction in terms of Pt + Ru mass as well as electroactive Pt + Ru surface area than the Pt/C and PtWO x /C catalysts. The addition of tungsten appeared to mainly result in some 'physical' modification of the catalytically active Pt and Ru surface components such as differences in electroactive surface area rather than promotion of the CH 3 OH oxidation reaction via a true catalytic mechanism.

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“…The former peak was attributed to the binding energy of 71.3 eV for metallic Pt and the latter was close to the binding energy of 72.3 eV for PtO. 10,15,16) In addition, the latter intensity was considerably weaker than the former one. Therefore, it was estimated that the thin film produced in the 100% Ar plasma was primarily composed of metallic Pt.…”

Section: Co Stripping Voltammetrymentioning

confidence: 72%

H<sub>2</sub> Oxidation Activity and Tolerance to CO Poisoning of the Electrochemically Reduced Pt Oxide Catalyst

2015

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In order to develop a novel anode catalyst for a PEFC, the Pt thin film and the Pt oxide thin film were produced by reactive sputtering, and the catalytic activity of the H 2 oxidation in the presence of CO or the tolerance to the CO poisoning was evaluated by the anodic polarization in an H 2 -saturated H 2 SO 4 solution or a (H 2 + CO)-saturated one. The H 2 oxidation activity of the Pt thin film remarkably deteriorated due to the CO poisoning. On the other hand, the electrochemical reduction produced a tolerance to the CO poisoning during the H 2 oxidation of the Pt oxide thin film. For the Pt oxide thin film electrochemically reduced at ¹0.3 C, the H 2 oxidation current in a (H 2 + 100 ppm CO)-saturated solution remained at the same level as in the H 2 -saturated one. The CO stripping voltammetry also revealed that the CO coverage was only 0.15 for the electrochemically reduced Pt oxide thin film although the CO coverage on the Pt thin film was calculated to be 0.95. Therefore, the electrochemically reduced Pt oxide may be a promising anode catalyst of the PEFC having a tolerance to CO poisoning. Moreover, the XPS analysis showed that there was a distinct difference in the chemical bonding state between the Pt thin film and the electrochemically reduced Pt oxide thin film. That is, a large spectrum due to the Pt-O bond was detected for the electrochemically reduced Pt oxide thin film, while the spectrum scarcely appeared for the Pt thin film. These results suggested that the residual oxygen might improve the tolerance to the CO poisoning during the H 2 oxidation of the electrochemically reduced Pt oxide thin film.

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ESCA study of sputtered platinum films

Cited by 269 publications

References 12 publications

Near Surface Phase Transition of Solute Derived Pt Monolayers

Near Surface Phase Transition of Solute Derived Pt Monolayers

The role of the WO_xad-component to Pt and PtRu catalysts in the electrochemical CH₃OH oxidation reaction

H<sub>2</sub> Oxidation Activity and Tolerance to CO Poisoning of the Electrochemically Reduced Pt Oxide Catalyst

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ESCA study of sputtered platinum films

Cited by 269 publications

References 12 publications

Near Surface Phase Transition of Solute Derived Pt Monolayers

Near Surface Phase Transition of Solute Derived Pt Monolayers

The role of the WOxad-component to Pt and PtRu catalysts in the electrochemical CH3OH oxidation reaction

H<sub>2</sub> Oxidation Activity and Tolerance to CO Poisoning of the Electrochemically Reduced Pt Oxide Catalyst

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The role of the WO_xad-component to Pt and PtRu catalysts in the electrochemical CH₃OH oxidation reaction