A molecular beam study of the adsorption and desorption of oxygen from a Pt(111) surface

Campbell, Charles T.; Ertl, G.; Kuipers, Harmjan; Segner, J.

doi:10.1016/0039-6028(81)90622-1

Cited by 461 publications

(232 citation statements)

References 45 publications

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“…This oxide has been identified by X-ray diffraction as a-PtO 2 [27,28] which decomposes at temperatures between 700 and 800 K [29]. These results differ from those obtained in UHV studies as no oxide formation has been observed on platinum in a similar temperature range [1,4,6,[30][31][32]. It is also opportune to note that the formation of platinum ''oxide'' state has been reported previously, albeit at considerably higher temperatures (900-1,100 K) [33].…”

Section: Introductionmentioning

confidence: 67%

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: Introductionmentioning

confidence: 67%

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

et al. 2011

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“…Usually, single crystals were used in these studies to serve as model surfaces. Figure 1 5 surface atoms (14)(15)(16). Figure 1c shows atoms had a reaction probability of unitythat is, every hydrogen molecule was dissociated when scattered from the stepped platinum surface (19; 26).…”

Section: Phenomena Revealed By Surface Science Studies In Vacuummentioning

confidence: 99%

Concepts, instruments, and model systems that enabled the rapid evolution of surface science

Somorjai

Park

2009

Surface Science

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Over the past forty years, surface science has evolved to become both an atomic scale and a molecular scale science. Gerhard Ertl's group has made major contributions in the field of molecular scale surface science, focusing on vacuum studies of adsorption chemistry on single crystal surfaces. In this review, we outline three important aspects that led to the recent advances of surface chemistry: the development of concepts, in situ instruments for molecular scale surface studies at buried interfaces (solid-gas and solidliquid), and new model nanoparticle surface systems in addition to single crystals.Combined molecular beam surface scattering and low energy electron diffraction (LEED)-surface structure studies on metal single crystal surfaces revealed new concepts, including adsorbate-induced surface restructuring and the unique activity of defects, atomic steps and kinks on metal surfaces. We have combined high pressure catalytic reaction studies with ultrahigh vacuum (UHV) surface characterization techniques using the UHV chamber equipped with a high-pressure reaction cell. New instruments, such as high pressure sum frequency generation (SFG) vibrational spectroscopy and scanning tunneling microscopy (STM) have been built that permit molecular-level surface studies performed at pressures. Tools that can access broad ranges of pressures can be used for both the in situ characterization of buried interfaces of solid-gas and solid-liquid and the study of catalytic reaction intermediates. The model systems for the study of molecular 2 surface chemistry have evolved from single crystals to nanoparticles in the 1-10 nm size range, which are the preferred media in catalytic reaction studies.

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Section: Introductionmentioning

confidence: 98%

“…This error in reflectivity led to a 40% error in the adsorption energies originally reported. We use our more accurate reflectivity of 76% to recalibrate their oxygen adsorption enthalpy data and show that it gives nearly identical results below 0.15 ML to the heats of adsorption determined from the temperature programmed desorption (TPD) experiments of two separate groups (Campbell et al 2 and Parker et al3 ). Differences arise above 0.15 ML, but we attribute these to the very low sticking probability of O 2,g on Pt(111) (< 0.05) above 0.15ML, which can lead to large errors in the adsorption energies measured by calorimetry.…”

mentioning

confidence: 97%

Energetics of Oxygen Adatoms, Hydroxyl Species and Water Dissociation on Pt(111)

Karp¹,

Campbell²,

Studt

et al. 2012

J. Phys. Chem. C

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Calorimetric measurements of the adsorption enthalpy of O 2,g to make 2 O ad on Pt(111) were performed by Fiorin et al..1 However, we show that they used a calibration value for the optical reflectivity of Pt(111) that was incorrectly reported in the literature. This error in reflectivity led to a 40% error in the adsorption energies originally reported. We use our more accurate reflectivity of 76% to recalibrate their oxygen adsorption enthalpy data and show that it gives nearly identical results below 0.15 ML to the heats of adsorption determined from the temperature programmed desorption (TPD) experiments of two separate groups (Campbell et al. 2 and Parker et al.3 ). Differences arise above 0.15 ML, but we attribute these to the very low sticking probability of O 2,g on Pt(111) (< 0.05) above 0.15ML, which can lead to large errors in the adsorption energies measured by calorimetry. Given this, we propose that the most reliable values for the adsorption enthalpy of oxygen on Pt(111) up to ¼ ML are those derived from TPD experiments, rather than the more recent calorimetry data. The best values are well described by (217-151θ) kJ/mol O 2 below ¼ ML, where θ is the O ad coverage in ML (i.e., O ad per Pt surface atom). We also report calculations of coverage-dependent adsorption energies for oxygen on Pt(111) from density functional theory (DFT) and find the results to be an average of 21 kJ/mol higher than the integral heats measured by TPD. We further use these corrected adsorption enthalpies to amend the energetics of hydroxyl species on Pt(111) that we previously measured 4 . This gives revised values for the standard enthalpies of formation of the coadsobed (D 2 O-OD) ad complex of -511 ± 7 kJ/mol and a Pt-OD bond energy of 248 ± 7 kJ/mol for the OD species within this complex. DFT compares reasonably well, calculating an enthalpy of formation for the (H 2 O-OH) ad complex of -456 kJ/mol and an O-Pt bond energy of 217 kJ/mol for the OH species within this complex. These revised values are used to estimate reaction enthalpies for the dissociation of adsorbed water and hydroxyl on Pt(111), and compared to DFT.

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A molecular beam study of the adsorption and desorption of oxygen from a Pt(111) surface

Cited by 461 publications

References 45 publications

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

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

Concepts, instruments, and model systems that enabled the rapid evolution of surface science

Energetics of Oxygen Adatoms, Hydroxyl Species and Water Dissociation on Pt(111)

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