Ordered structures of CO on Pd(111) studied by STM

Rose, M.; Mitsui, Toshiyuki; Dunphy, J.C.; Borg, A.; Ogletree, D. Frank; Salmerón, Miquel; Sautet, Philippe

doi:10.1016/s0039-6028(02)01560-1

Cited by 116 publications

(179 citation statements)

References 19 publications

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“…For Cu(111) the use of the correction gives the experimental site preference [24,33], though the corrected DFT results predict small (≤ 0.1 eV) differences between the top, bridge and hollow sites. Both the raw DFT and the corrected results for Pd(111) agree with the site preference observed by experiment [23,34,35]. Our corrected results for the (100) surfaces agree with experimentally observed preferred adsorption sites for Pt [36,37,38], Rh [39,40], Pd [38,41], and Cu [42,43].…”

Section: Resultssupporting

confidence: 86%

First-principles extrapolation method for accurate CO adsorption energies on metal surfaces

2004

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We show that a simple first-principles correction based on the difference between the singlettriplet CO excitation energy values obtained by DFT and high-level quantum chemistry methods yields accurate CO adsorption properties on a variety of metal surfaces. We demonstrate a linear relationship between the CO adsorption energy and the CO singlet-triplet splitting, similar to the linear dependence of CO adsorption energy on the energy of the CO 2π* orbital found recently [Kresse et al., Physical Review B 68, 073401 (2003)]. Converged DFT calculations underestimate the CO singlet-triplet excitation energy ∆ES−T, whereas coupled-cluster and CI calculations reproduce the experimental ∆ES−T. The dependence of E chem on ∆ES−T is used to extrapolate E chem for the top, bridge and hollow sites for the (100) and (111) surfaces of Pt, Rh, Pd and Cu to the values that correspond to the coupled-cluster and CI ∆ES−T value. The correction reproduces experimental adsorption site preference for all cases and obtains E chem in excellent agreement with experimental results.

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Section: Resultssupporting

confidence: 86%

First-principles extrapolation method for accurate CO adsorption energies on metal surfaces

2004

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“…For Cu(111), the experimental values are in the range of −0.52 to −0.46 eV, 58,59 close to our calculated value (≈ −0.60 eV). For Rh(111), they are between −1.65 and −1.43 eV 60,61 .…”

Section: Co Adsorption: Energetics and Structural Propertiessupporting

confidence: 89%

CO adsorption on metal surfaces: A hybrid functional study with plane-wave basis set

et al. 2007

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“…Only the top site CO molecules were resolved by STM due to higher tunneling probability, similar to observations on other metals [34,52]. The corrugation and periodicity of the observed (2 x 2) agreed with that of the (2 x 2)-3CO formed on Rh(111) under high pressure of pure CO [49].…”

Section: Co Poisoning Of Ethylene Hydrogenation On Rh(111)supporting

confidence: 81%

High Pressure Scanning Tunneling Microscopy Studies of AdsorbateStructure and Mobility during Catalytic Reactions: Novel Design of anUltra High Pressure, High Temperature Scanning Tunneling MicroscopeSystem for Probing Catalytic Conversions

Tang¹

2005

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The aim of the work presented therein is to take advantage of scanning tunneling microscope's (STM) capability for operation under a variety of environments under real time and at atomic resolution to monitor adsorbate structures and mobility under high pressures, as well as to design a new generation of STM systems that allow imaging in situ at both higher pressures (35 atm) and temperatures (350 °C).The design of a high pressure, high temperature scanning tunneling microscope system, that is capable of monitoring reactions in situ at conditions from UHV and ambient temperature up to 1 atm and 250 °C, is briefly presented along with vibrational 2 and thermal analysis, as this system serves as a template to improve upon during the design of the new ultra high pressure, high temperature STM.Using this existing high pressure scanning tunneling microscope we monitored the co-adsorption of hydrogen, ethylene and carbon dioxide on platinum (111) and rhodium (111) crystal faces in the mTorr pressure range at 300 K in equilibrium with the gas phase. During the catalytic hydrogenation of ethylene to ethane in the absence of CO the metal surfaces are covered by an adsorbate layer that is very mobile on the time scale of STM imaging. We found that the addition of CO poisons the hydrogenation reaction and induces ordered structures on the single crystal surfaces. Several ordered structures were observed upon CO addition to the surfaces pre-covered with hydrogen and ethylene: a rotated (√19 x √19)R23.4° on Pt(111), and domains of c(4 x 2)-CO+C 2 H 3 , previously unobserved (4 x 2)-CO+3C 2 H 3 , and (2 x 2)-3CO on Rh(111). A mechanism for CO poisoning of ethylene hydrogenation on the metal single crystals was proposed, in which CO blocks surface metal sites and reduces adsorbate mobility to limit adsorption and reaction rate of ethylene and hydrogen.In order to observe heterogeneous catalytic reactions that occur well above ambient pressure and temperature that more closely resemble industrial settings, a custom STM motor has been designed and constructed in-house. The new STM design features a much reduced size and a rigid coupling to the sample, and has been tested to show considerably higher resonance frequency than conventional tripod designs, providing the ability to image faster and yielding smaller susceptibility to noise. A flow reactor cell of much reduced volume for pressures up to 35 atmospheres has also been designed and 3 constructed to house the new STM. The small volume reduces gas consumption and sensitivity to impurities in high pressure gases, as well as maximizes product concentration and reduces response time. The ability to flow reactant gases also allows for continuous monitoring of reaction mixture by mass spectrometry or gas chromatography, and permits correlation of structural information from STM and reaction kinetics. The reactor cell containing the STM is placed inside an UHV system to allow cleaning and characterization of sample before and after experiments, as well as continuous monitoring by m...

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Ordered structures of CO on Pd(111) studied by STM

Cited by 116 publications

References 19 publications

First-principles extrapolation method for accurate CO adsorption energies on metal surfaces

First-principles extrapolation method for accurate CO adsorption energies on metal surfaces

CO adsorption on metal surfaces: A hybrid functional study with plane-wave basis set

High Pressure Scanning Tunneling Microscopy Studies of AdsorbateStructure and Mobility during Catalytic Reactions: Novel Design of anUltra High Pressure, High Temperature Scanning Tunneling MicroscopeSystem for Probing Catalytic Conversions

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