Correlation between local substrate structure and local chemical properties: CO adsorption on well-defined bimetallic surfaces

Gleich, B.; Ruff, M.; Behm, R. Jürgen

doi:10.1016/s0039-6028(97)00302-6

Cited by 69 publications

(61 citation statements)

References 17 publications

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“…The disappearance of the 259 meV signal is easily explained by the low adsorption energy of CO adsorbed on Pd atop sites, e.g., on Pd monomers. 18 The absence of the weak signal at 131 meV, which we related to an H ad band, is most easily explained by the lower H ad coverage under these conditions, possibly in combination with a change in the vibrational cross section. 63 Finally, we performed CO titration experiments on the Pd 21 Au 79 surface (Fig.…”

Section: Adsorption and Desorption Of Hydrogen On Pdau-pd(111) Surfacmentioning

confidence: 77%

“…Other loss peaks (227, 237 and 259 meV), whose intensity increased with increasing data acquisition time, are assigned to the C-O stretch mode of CO adsorbed on various Pd sites, which is accumulated from the residual gas. 18 Spectra recorded at room temperature (Fig. 5b) also showed a loss peak at 96 meV, indicating that also under these conditions there are H atoms adsorbed on the Pd 3 threefold hollow sites of the Pd 38 Au 62 surface.…”

Section: Adsorption and Desorption Of Hydrogen On Pdau-pd(111) Surfacmentioning

confidence: 84%

“…The latter include a differentially pumped mass spectrometer for TPD measurements, as well as spectrometers for HREELS and X-ray photoelectron spectroscopy (XPS), and a low energy electron diffraction (LEED) system. 18 The mass spectrometer was covered by a Au coated snout with an aperture of 2 mm in diameter. 54 The distance between the aperture and the sample was fixed to less than 1 mm by a spacer.…”

Section: Methodsmentioning

confidence: 99%

“…5b) also showed a loss peak at 96 meV, indicating that also under these conditions there are H atoms adsorbed on the Pd 3 threefold hollow sites of the Pd 38 Au 62 surface. In addition to the H ad related feature, the spectra showed an additional loss peak at 42 meV (M-CO stretch 18 ). The weak signal at 131 meV and the signal at 259 meV do not appear at room temperature.…”

Section: Adsorption and Desorption Of Hydrogen On Pdau-pd(111) Surfacmentioning

confidence: 99%

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Hydrogen adsorption on bimetallic PdAu(111) surface alloys: minimum adsorption ensemble, ligand and ensemble effects, and ensemble confinement

Takehiro

Liu

Bergbreiter

et al. 2014

Phys. Chem. Chem. Phys.

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The adsorption of hydrogen on structurally well defined PdAu-Pd(111) monolayer surface alloys was investigated in a combined experimental and theoretical study, aiming at a quantitative understanding of the adsorption and desorption properties of individual PdAu nanostructures. Combining the structural information obtained by high resolution scanning tunneling microscopy (STM), in particular on the abundance of specific adsorption ensembles at different Pd surface concentrations, with information on the adsorption properties derived from temperature programmed desorption (TPD) spectroscopy and high resolution electron energy loss spectroscopy (HREELS) provides conclusions on the minimum ensemble size for dissociative adsorption of hydrogen and on the adsorption energies on different sites active for adsorption. Density functional theory (DFT) based calculations give detailed insight into the physical effects underlying the observed adsorption behavior. Consequences of these findings for the understanding of hydrogen adsorption on bimetallic surfaces in general are discussed.

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Section: Adsorption and Desorption Of Hydrogen On Pdau-pd(111) Surfacmentioning

confidence: 77%

Section: Adsorption and Desorption Of Hydrogen On Pdau-pd(111) Surfacmentioning

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Section: Adsorption and Desorption Of Hydrogen On Pdau-pd(111) Surfacmentioning

confidence: 99%

See 2 more Smart Citations

Hydrogen adsorption on bimetallic PdAu(111) surface alloys: minimum adsorption ensemble, ligand and ensemble effects, and ensemble confinement

Takehiro

Liu

Bergbreiter

et al. 2014

Phys. Chem. Chem. Phys.

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“…A correlation between the d-band center of transition metal and alloy surfaces and the chemisorption energy of CO and other small molecules has been established [32,34]. Enhanced CO adsorption energies at surface defect sites of bimetallic surfaces, such as atomic step edges or kinks, has been found recently, which was attributed to the reduced coordination of these metal sites [35][36][37].…”

Section: Adsorption Processmentioning

confidence: 99%

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Weiß

Ranke

2002

Progress in Surface Science

584

610

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Metal-oxide based catalysts are used for many important synthesis reactions in the chemical industry. A better understanding of the catalyst operation can be achieved by studying elemantary reaction steps on well-defined model catalyst systems. For the dehydrogenation of ethylbenzene to styrene in the presence of steam both unpromoted and potassium promoted iron-oxide catalysts are active. Here we review the work done over unpromoted single-crystalline FeO(111), Fe 3 O 4 (111) and α-Fe 2 O 3 (0001) films grown epitaxially on Pt(111) substrates. Their geometric and electronic surface structures were characterized by STM, LEED, electron microscopy and electron spectroscopic techniques. In an integrative approach, the interaction of water, ethylbenzene and styrene with these films was investigated mainly by thermal desorption and photoelectron emission spectroscopy. The adsorptiondesorption energetics and kinetics depend on the oxide surface terminations and are correlated to the electronic structures and acid-base properties of the corresponding oxide phases, which reveal insight into the nature of the active sites and into the catalytic function of semiconducting oxides in general. Catalytic studies, using a batch reactor arrangement at high gas pressures and post reaction surface analysis, showed that only α-Fe 2 O 3 (0001) containing surface defects is catalytically active, whereas Fe 3 O 4 (111) is always inactive. This can be related to the elementary adsorption and desorption properties observed in ultrahigh vacuum, which indicates that the surface chemical properties of the iron-oxide films do not change significantly across the "pressure-gap". A model is proposed according to which the active site involves a regular acidic surface sites and a defect site next to it. The results on metal-oxide surface chemistry also have implications for other fields, such as environmental science, biophysics and chemical sensors.-2 -"2kyEi9FYSQjBVrZxIPQ.FHIAC_WRa02_review.doc", Datum: 19.02.03

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Ex‐situ surface preparation and analysis: transfer betweenUHVand electrochemical Cell

Hoster¹,

Gasteiger²

2010

Handbook of Fuel Cells

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The further optimization of electrode materials for fuel cells in laboratory studies offers two main approaches: (i) improving the understanding of the microscopic electrode processes by observation with in‐situ and ex‐situ methods; and (ii) the systematic compositional and structural variation of surfaces to create model electrodes for electrocatalytic measurements. The ultra high vacuum (UHV) environment offers unique possibilities for both surface preparation and analysis and has thus been used extensively in recent electrocatalytical research work. At the same time, methods allowing the in‐situ observation of electrochemical processes has also gone through impressive advances in recent years, and in many cases it has been found that earlier ex‐situ results obtained in UHV needed to be revised due to changes of the electrode surfaces during the transfer into UHV. In the following we will discuss some of the most frequently applied ex‐situ methods in electrocatalytic research and review some of the important aspects concerning the reliability of the resulting data. Utilizing a number of examples, we will demonstrate how such combined UHV electrochemistry experiments can be technically realized, including a discussion of commonly encountered practical problems. We will further point out the advantages offered by the electrocatalytical characterization of UHV designed and UHV characterized model electrodes. In our opinion, this is a very promising approach to UHV/electrochemistry experimentation: on the one hand, the uncertainties due to the transfer between UHV and electrochemical environment are less significant compared to emersion experiments of adsorbed adlayers; on the other hand, well‐established UHV preparation techniques combined with structural characterization tools (atomic force microscopy (AFM)/scanning tunneling microscopy (STM)) provide the possibility of precisely tailoring defined model electrodes. Some examples from research on anode catalysts are given to illustrate this unique capability of UHV electrochemistry setups as powerful tool for the systematic tailoring of model electrodes.

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Correlation between local substrate structure and local chemical properties: CO adsorption on well-defined bimetallic surfaces

Cited by 69 publications

References 17 publications

Hydrogen adsorption on bimetallic PdAu(111) surface alloys: minimum adsorption ensemble, ligand and ensemble effects, and ensemble confinement

Hydrogen adsorption on bimetallic PdAu(111) surface alloys: minimum adsorption ensemble, ligand and ensemble effects, and ensemble confinement

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Ex‐situ surface preparation and analysis: transfer betweenUHVand electrochemical Cell

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