Oxidation of Pt(111) by ozone (O3) under UHV conditions

Saliba, Najat A.; Tsai, Yi-Li; Panja, Chameli; Koel, Bruce E.

doi:10.1016/s0039-6028(98)00667-0

Cited by 98 publications

(146 citation statements)

References 39 publications

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“…300 K dose corresponds to an O coverage of 0.48 (±0.04) ML. As 0.25 ML is the maximum coverage that can be obtained for dissociation of O 2 at 300 K, we conclude that during the initial high-temperature exposure, oxygen is adsorbed in positions that do not block sites for consecutive dissociative adsorption of O 2 at 300 K. Enhanced oxygen coverage was previously obtained on Pt(111) in a number of TPD studies in which NO 2 , O 3 and O where used as the source of atomically adsorbed oxygen [19,21,38]. For low doses, oxygen adsorbs into the same p(2 9 2) structure as for O 2 dosing at room temperature [8,17,38].…”

Section: Resultssupporting

confidence: 61%

“…Therefore, coverages up to 0.75 ML of atomic oxygen can be achieved by dissociation of NO 2 on Pt(111) at 400 K [3,[16][17][18]. Even higher coverages (up to 2.5-2.9 ML) can be produced by exposure to more aggressive oxidants, such us ozone [19] and atomic oxygen [20,21]. In combination with DFT calculations, it has been shown that oxygen adsorption on Pt(111) up to the coverage of 0.4-0.5 ML precedes the growth of a thicker platinum oxide layer [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

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Subsurface Oxygen on Pt(111) and Its Reactivity for CO Oxidation

et al. 2011

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Temperature has an important effect on the dissociative adsorption of molecular oxygen on platinum surfaces. Here, we show that if the substrate temperature is increased to 400-600 K, the total amount of oxygen loaded onto Pt(111) can be more than twice the well-established maximum coverage of 0.25 ML. While low energy electron diffraction and STM reveal a conventional p(2 9 2) structure of the topmost layer, temperature programmed desorption measurements indicate that additional oxygen is stored under the surface of platinum. Reactivity measurements show that this sub-surface oxygen layer does not lower the activity of such platinum surface towards CO oxidation. Therefore, while sub-surface oxygen layer does form under catalytically relevant temperatures on Pt(111), it has no great influence on the oxidizing ability of such surface. This sheds new light on the initial stages of platinum oxide formation, and may help bridge the understanding of catalytic oxidation of CO on Pt in ultra high vacuum and in high-pressure catalysis studies.

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Section: Resultssupporting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Subsurface Oxygen on Pt(111) and Its Reactivity for CO Oxidation

et al. 2011

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“…Platinum forms two oxides of comparable stability: a CdI 2 -type a-PtO 2 [19] and a rutile-like CaCl 2 -type b-PtO 2 [20]. The formation of Pt-oxide islands or overlayers is corroborated by the large O uptake over Pt(1 1 1) after exposure to ozone [21], by detection with X-ray photoelectron spectroscopy of an oxidic oxygen state after exposure of Pt(1 1 1) to atomic O [22], and by Fourier transformed infrared and X-ray absorption near-edge structure spectroscopy investigations of a model catalyst [23]. Recent surface X-ray diffraction results from the Frenken group further indicate that the a-PtO 2 forms over the Pt(1 1 1) [24] and we hence chose this structure for the oxide phase.…”

Section: Structure Of Three-phase Boundarymentioning

confidence: 97%

Reactivity of a gas/metal/metal-oxide three-phase boundary: CO oxidation at the Pt(111)–c(4×2)-2CO/α-PtO2 phase boundary

Hammer

2005

Chemical Physics Letters

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“…[50][51][52][53] Therefore, the presence of such surface platinum oxides can be assumed in most cases (especially when exposure to ambient is involved), and the interaction of thiols with these oxides will likely play a role in SAM formation and stability.…”

Section: Platinum Oxidementioning

confidence: 99%

Alkanethiols on Platinum: Multicomponent Self-Assembled Monolayers

et al. 2006

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We have studied the formation of self-assembled monolayers (SAMs) of n-alkanethiols on platinum thin films using X-ray photoelectron spectroscopy (XPS), reflection-absorption infrared spectroscopy (RAIRS), spectroscopic ellipsometry (SE), and contact angle (CA) measurements. Specifically, SAMs of 1-hexanethiol, 1-dodecanethiol, and 1-octadecanethiol were grown on polycrystalline Pt films, and the effects of Pt surface preparation, deposition conditions, and solvent treatments on the initial quality and stability of the monolayer in air were investigated. The SAMs prepared under ambient conditions on piranha-cleaned and UV/ozone-cleaned substrates were compared to monolayers formed on template-stripped Pt in an inert atmosphere. We found that alkanethiols deposited from 1 mM ethanolic solutions on piranha-cleaned Pt formed densely packed monolayers in which alkyl chains were oriented close to the surface normal. Stored in the laboratory ambient, these monolayers were unchanged over about 1 week but were largely oxidized in about 1 month. No evidence was found of molecules being weakly bound within the monolayer or having undergone C-S bond scission; however, three distinct sulfur states were observed for all samples in the XPS of the S 2p region. The lowest-and highest-binding-energy components are assigned to alkylthiolate and partially oxidized alkylthiolate species, respectively. The remaining S 2p component (approximately one-third of the sulfur layer), intermediate in binding energy between the other two components, is attributed to a chemisorbed species with a S binding configuration distinct from the majority alkylthiolate: for example, S bound to Pt bound to O, S with a different Pt coordination number, or S in an adsorbed disulfide.

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Oxidation of Pt(111) by ozone (O3) under UHV conditions

Cited by 98 publications

References 39 publications

Subsurface Oxygen on Pt(111) and Its Reactivity for CO Oxidation

Subsurface Oxygen on Pt(111) and Its Reactivity for CO Oxidation

Reactivity of a gas/metal/metal-oxide three-phase boundary: CO oxidation at the Pt(111)–c(4×2)-2CO/α-PtO2 phase boundary

Alkanethiols on Platinum: Multicomponent Self-Assembled Monolayers

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