Adsorbate Reorganization at Steps: NO on Pd(211)

Hammer, Bjørk; Nørskov, Jens K.

doi:10.1103/physrevlett.79.4441

Cited by 71 publications

(56 citation statements)

References 13 publications

(12 reference statements)

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“…Any adsorbate which is attracted to a step atom by an energy comparable to the step formation energy should induce disordering on any facet. CO also binds strongly to steps of other Pt surfaces [16], and the same has been established for NO, O, N, and C on a number of different transition metals [17][18][19]. The underlying reason is that the step atoms with a low coordination number have high energy d electrons, which interact more strongly with adsorbate states [20,21].…”

Section: -3mentioning

confidence: 69%

Adsorption-Induced Step Formation

et al. 2001

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Section: -3mentioning

confidence: 69%

Adsorption-Induced Step Formation

et al. 2001

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“…These The Journal of Physical Chemistry C ARTICLE changes in the metal d-bands can be caused by forming alloys or overlayers or by changing the coordination state of the metal atom. 79,80 Our results are shown in Figure 8 for the six bare clusters and for CO in vacuum. Here, the energies are all referenced to the vacuum level, and the black vertical lines in each panel indicate the position of the Fermi level in the corresponding bare metal cluster.…”

Section: 50mentioning

confidence: 95%

CO Adsorption on Noble Metal Clusters: Local Environment Effects

et al. 2011

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Bimetallic catalysts are useful because of their versatility, such as the ability to tune their catalytic activity and selectivity by varying properties such as composition, particle size, and support. 1 In particular, Pt-Au catalysts have been shown to exhibit enhanced activity and selectivity in specific reactions when compared to monometallic catalysts. For example, Dimitratos et al. 2 showed that carbon-supported Pt-Au has higher catalytic activity for the oxidation of glycerol than carbon-supported Pt and that the catalyst preparation method affects the selectivity. Selvarani et al. 3 determined that the optimum Pt:Au ratio for carbon-supported Pt-Au as a direct methanol fuel cell catalyst is 2:1, at which composition the catalyst delivers a peak power density 1.5 times that of pure Pt. Comotti et al. 4 found a turnover frequency of 60 h -1 for the oxidation of glucose over pure platinum, while a Pt-Au alloy with Au:Pt ratio of 2:1 yields a turnover frequency of 924 h -1 . The authors also found that, for 7 different Au:Pt ratios ranging from 4 to 0.25, the minimum and maximum turnover frequencies are 240 and 924 h -1 , observed for Au:Pt ratios of 1 and 2, respectively. It is likely that these results depend on the atomic arrangement on the surface of the bimetallic nanoparticles used as catalysts. Unfortunately, direct experimental visualization of the composition and structure of nanoparticle surfaces is at present problematic, especially at operating conditions. Techniques such as high-energy resonant X-ray diffraction can be used to probe the structure of bimetallic catalysts. 5 Molecular simulations could be useful to interpret such experiments and also identify the local structure of supported mono-and bimetallic nanoparticles. [6][7][8] For example, we have previously used molecular dynamics (MD) simulations to study the effect of composition and support geometry on the properties of Pt-Au nanoparticles containing 250 atoms, 9 finding that it should be possible to tailor the distribution of atoms by manipulating nanoparticle composition and support geometry. This could lead to greater control of catalyst selectivity by maximizing the active sites on the nanoparticle surface that catalyze a certain reaction.In order to link our previous MD results to experimentally verifiable measurements, we report here ab initio density functional theory (DFT) calculations for CO adsorption on Pt-Au clusters. CO is often employed as a probe molecule because its adsorption energy and C-O stretching frequency depend on the adsorption site, as can be observed experimentally via, e.g., Fourier transform infrared spectroscopy. 10 CO adsorption is also important in CO oxidation, which occurs in automobile catalytic converters, 11 in preferential CO oxidation (PROX reaction) in hydrogen feeds, 12 and in CO hydrogenation, the critical step in Fischer-Tropsch processes. 13 DFT has been used to study adsorption of CO on metal surfaces, such as Pt(111), [14][15][16][17] on Pt(111) overlayers, 18,19 and on metal nanoparticles. ...

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“…Since several competing factors may influence a chemical reaction, the strategy over the years has been to isolate the role of the geometrical, structural and compositional characteristics that are expected to be important. Among these, the influence of steps [1][2][3][4][5][6][7][8] and impurities 9,10 on the electronic and geometric structure of transition metal surfaces has been of great interest. This is not surprising since steps are omnipresent, even under reasonably controlled conditions.…”

Section: Introductionmentioning

confidence: 99%

Site selectivity in chemisorption of C on Pd(211)

et al. 2004

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Site selectivity in chemisorption of C on Pd(211) Results of ab initio electronic structure calculations of C on Pd(211), a vicinal of Pd (111), show a hierarchy of adsorption sites with adsorption energy ranging from −8.21 to − 5.46 eV (0.33 ML coverage) and scaling almost linearly with the effective coordination at the site. In the most preferred site, C atoms sit almost under the Pd step atoms and influence drastically multilayer relaxations and surface registry of Pd(211). The adsorption energy at this site is −9.10 eV for 0.17 ML coverage. The local densities of electronic states indicate strong hybridization between C p states and neighboring Pd d states leading to the formation of strong covalent C u Pd bonds. The depletion of the electronic density of states of the Pd surface atoms at the Fermi level suggests a poisoning effect of C which is found to be coverage dependent. We compare the changes in the electronic structure of Pd(211) on C adsorption with those on S adsorption.

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Adsorbate Reorganization at Steps: NO on Pd(211)

Cited by 71 publications

References 13 publications

Adsorption-Induced Step Formation

Adsorption-Induced Step Formation

CO Adsorption on Noble Metal Clusters: Local Environment Effects

Site selectivity in chemisorption of C on Pd(211)

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