CO Adsorption on Au(110)−(1 × 2):  An IRAS Investigation

Meier, Douglas C.; Bukhtiyarov, Valerii I.; Goodman, D. W.

doi:10.1021/jp030499u

Cited by 94 publications

(117 citation statements)

References 28 publications

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“…34 The infrared data can be interpreted in terms of surface coverage (described in detail below) and are plotted in Figure 4. Extrapolation of this plot to θ ) 1 yields a full-coverage CO stretching frequency of 2103.5 cm -1 , in excellent agreement with measurements on model UHV systems 19,[22][23][24][25] and higherpressure studies with other supported Au catalysts. 26 The integrated peak area (S) was used to quantify the CO adsorption.…”

Section: Resultssupporting

confidence: 81%

“…Although this model may be an oversimplification, there are a number of literature reports describing two different CO adsorption regimes on model gold catalysts. 24,25,42 Alternately, a Langmuir model with a coverage-dependent binding constant (and therefore binding energy) can be used to explain the differences in CO binding energy at low and high coverage. The fitting is accomplished using a sliding-tangent Langmuir expression, which also does a good job of describing the experimental data (the solid line through the data in Figure 6 nearly overlaps the two-site model fit).…”

Section: Discussionmentioning

confidence: 99%

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Adsorption of CO on Supported Gold Nanoparticle Catalysts: A Comparative Study

2009

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The adsorption of CO on three different gold nanoparticle catalysts supported on high surface area TiO 2 was studied using infrared transmission spectroscopy at room temperature and CO pressures typically used in CO oxidation reactions. The three, real-world catalysts were Au catalysts synthesized in our laboratory from thiol monolayer protected clusters (MPCs) and two commercial catalysts from the World Gold Council (WGC and AuTEK). Within experimental reproducibility, the adsorption data for the three catalysts are indistinguishable. While showing approximately Langmuir behavior, the adsorption data also show coverage dependence, as others have observed for many catalyst systems. Two approaches were used to fit the data, a two-site model and a variable binding constant model. The two-site Langmuir model yielded strong (36%) and weak (64%) binding constants of 2740 and 146 atm -1 , respectively. Alternatively, using a sliding-tangent Langmuir fit gave a variable binding constant of 2670-120 atm -1 at room temperature for coverage θ ) 0-0.8. The heat of adsorption was then extracted from the binding constants using a literature value for -T∆S. These values were determined as ∆H ) -64 and -56 kJ/mol for strong and weak binding according to the two-site model and ∆H ) -63 to -56 kJ/mol for coverage θ ) 0-0.8 for the variable binding constant model. These values agree well with literature values obtained (i) using supported catalysts under higher pressures and (ii) using model catalysts under higher pressures and ultrahigh vacuum conditions.

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Section: Resultssupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Adsorption of CO on Supported Gold Nanoparticle Catalysts: A Comparative Study

2009

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“…The interpretation suggested above is fully consistent with that proposed by Goodman et al 9 for the same adsorption process on a Au(110) 1 © 2 reconstructed model surface at much lower temperature (100250 K) and CO partial pressure (1 © 10 ¹8 1 © 10 ¹4 Torr). As recently discussed, 41 this model surface actually consists of intersecting nanosized [111] planes in which sites with CN = 7 (25%), CN = 9 (50%), and CN = 11 (25%) coexist.…”

Section: ç 3 Nanostructural Analysis Of the Au Sites For Co Adsorptionsupporting

confidence: 90%

Recent Progress in Chemical Characterization of Supported Gold Catalysts: CO Adsorption on Au/Ceria–Zirconia

et al. 2011

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An approach correlating quantitative CO adsorption data with the nanostructural properties of Au/CeO 2 ZrO 2 catalysts is discussed. It has been used to show that the CO adsorption occurs on Au sites with coordination number¯7, that Au dispersion has a dramatic influence on the amount of CO strongly chemisorbed on the support, and that a fully reversible SMSI effect may be induced by successive mild reduction and reoxidation treatments. Ç 1. IntroductionThe discovery in 1987 by Haruta et al.1 that gold highly dispersed on appropriate oxide supports shows much higher CO oxidation activity than the analogous systems constituted by noble metals of Groups 810 represents a major breakthrough point in the history of the catalysis by gold.2 Following this, in principle, unexpected finding, 3 a dramatic increase in the number of published papers on gold catalysts has been observed. 4 Despite the big research effort devoted to this topic, many important questions about the ultimate origin of the exceptional behavior of gold remain open to discussion. 5The adsorption of the reactant molecules is acknowledged to be a key initial step of the heterogeneous catalytic processes. Accordingly, to gain detailed information about the surface chemistry of gold is certainly a relevant issue in order to arrive at a finer understanding of its catalytic behavior. As recently stressed, 2 until some 20 years ago, very little information was available on the chemisorptive properties of gold, the extreme nobility which was traditionally assumed to characterize this metal being invoked to justify this lack of studies. In the last two decades, however, the number of papers dealing with this topic has grown very rapidly, 2,6 a considerable amount of data being presently available. Though the adsorption of a relatively large number of molecules and atoms has been investigated, 6 CO is certainly one of the most commonly used probe molecules for gold surfaces. At present, the COAu interaction has been investigated on a variety of systems including massive single crystals, 612 small clusters or nanoparticles supported on both planar model, 1324 and powdered oxides.2534 Studies on the CO interaction with gas-phase Au clusters have also been reported. 3537 Depending on the specificities of the investigated systems, significantly different experimental conditions and techniques have been applied in the above-mentioned studies. Finally, CO adsorption on gold has also been investigated from a theoretical point of view. 1416,38,39 From all these studies a number of relevant conclusions have already been obtained. Thus, with reference to the noble metals of Groups 810, gold interaction with CO is much weaker.2,6 Consistently, it is generally acknowledged that the active sites for CO adsorption consist of defective, lowcoordination, surface gold atoms. 2,6,22,40 This represents a first problem very much limiting the conventional use of CO as a tool for characterizing gold surfaces. In the case of supported gold catalysts, the simultaneous occ...

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“…The adsorption of CO on bare Au single crystals of low Miller index such as (111), (100) and (110) has been explored in the past by various authors [20][21][22] . Even though these results were obtained by adsorbing CO at low temperatures, they provide an interesting framework to understand the reactiveness of Au surfaces.…”

Section: Resultsmentioning

confidence: 99%

“…In this sense, Meier et al 21 reported that for a Au (110) surface, for temperatures above 250 K, the adsorption of CO is discarded for by means of infrared reflection absorption spectroscopy data at pressures in the mbar range. These results agree very well with the absence of adsorbed CO on Au(332) observed from HRCL spectra of Figure 1b The role of under-coordinated atoms in the adsorptive properties of Au surfaces has been discussed by Mehmood et al 20 and the calculated energy of adsorption of CO on flat, stepped and kinked Au reveals a stronger adsorption on under-coordinated atoms; although, the energies of adsorption obtained are considerably smaller than for Pt surfaces.…”

Section: Resultsmentioning

confidence: 99%

Promotion Effect of Platinum on Gold’s Reactivity: A High-Resolution Photoelectron Spectroscopy Study

et al. 2016

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The reactivity of the Pt/Au(332) surface was studied using high resolution photoelectron spectroscopy and carbon monoxide adsorption at 3.5 x 10 -3 mbar. The characterization of Pt/Au (332) indicates the formation of a Au-Pt surface alloy at the top most atomic layer of the (332) crystal due to an atomic exchange mechanism at both terrace and step edge. The amount of alloyed Au atoms has proven to be dependent on the amount of Pt deposited in the coverage range investigated. The activation of Au atoms by alloying is detected by comparing the ability of the surface to adsorb CO at high pressures. By analyzing the C 1s and O 1s photoemission lines it is possible to conclude that CO adsorption is both dissociative and molecular on the PtAu/Au(332) surface, differently from the behavior observed for Au and Pt single crystals. Also, by rising the temperature of the COads-PtAu/Au(332) surface, a dissociative reaction path is followed with the accumulation of graphitic carbon on the surface and the oxygen desorption. Thus, our results shows, not only the differential catalytic behavior of Pt@Au/Au(hkl) model surfaces but also that Au atoms have an active role on the reaction mechanism.

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CO Adsorption on Au(110)−(1 × 2): An IRAS Investigation

Cited by 94 publications

References 28 publications

Adsorption of CO on Supported Gold Nanoparticle Catalysts: A Comparative Study

Adsorption of CO on Supported Gold Nanoparticle Catalysts: A Comparative Study

Recent Progress in Chemical Characterization of Supported Gold Catalysts: CO Adsorption on Au/Ceria–Zirconia

Promotion Effect of Platinum on Gold’s Reactivity: A High-Resolution Photoelectron Spectroscopy Study

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