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Shaikhutdinov, Shamil K.; Meyer, Randall J.; Naschitzki, Matthias; Bäumer, Marcus; Freund, Hans‐Joachim

doi:10.1023/a:1022616102162

Cited by 172 publications

(158 citation statements)

References 25 publications

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“…An assignment of the two desorption peaks in CO-TPD from the Au(211) and Au(332) surfaces to desorption from step sites ($190 K) and terraces ($130 K) seems unlikely, since the relative intensities of the two signals is about the same for both surfaces, despite the fact that the Au(332) surface contains about twice as much terrace sites compared the Au(211) surface. The higher edge/corner ratio on the Au/FeO system reflects the larger particle size on Au/FeO (5.0 nm) compared to the Au/Al 2 O 3 system (2.5 nm), as determined by STM [39]. The estimated CO adsorption energies, derived from the observed desorption temperature ranges, using the rate equation for first order desorption and assuming a pre-exponential factor between 10 11 and 10 15 s -1 , are 0.24-0.39 eV for the edge/ step sites (CN = 7), 0.34-0.…”

Section: The Importance Of the Au Coordination Numbermentioning

confidence: 92%

“…Au(110)-(1 · 2) surface [104], and Au nanoparticles on Au/FeO and Au/Al 2 O 3 [39]. A consistent interpretation of these results is that the desorption around 170-190 K corresponds to CO adsorbed on defect sites or corner sites, the desorption around 150 K corresponds to CO adsorption on the Au(110)-(1 · 2) surface, and the desorption around 110-130 K is due to CO adsorbed on edges of the nanoparticles, or step sites on the single crystal surfaces.…”

Section: The Importance Of the Au Coordination Numbermentioning

confidence: 99%

“…This implies that the observed general trend for the catalytic activity of supported Au catalysts can be explained by the expected amounts of Au corner atoms at the different Au particle sizes. [39]. Each trace has an arbitrary scaling, and does not reflect the absolute amounts of CO in the different systems, only relative intensities within a single curve can be used.…”

Section: Low Coordinated Au Atoms In Supported Au Catalystsmentioning

confidence: 99%

“…The first type of explanations associates the catalytic activity with the nature of the gold atoms in the particles. Both theory and experiments have pointed to the importance of lowcoordinated Au atoms acting as active sites [35][36][37][38][39][40][41][42][43][44][45][46][47]. A change in the electronic structure of gold, resulting in a metal-insulator transition has also been invoked [6,[48][49][50].…”

Section: Introductionmentioning

confidence: 99%

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Insights into the reactivity of supported Au nanoparticles: combining theory and experiments

et al. 2007

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The origin of the extraordinary catalytic activity of gold nanoparticles is discussed on the basis of density-functional calculations, adsorption studies on single crystal surfaces, and activity measurements on well characterized supported gold particles. A number of factors are identified contributing to the activity, and it is suggested that it is useful to consider lowcoordinated Au atoms as the active sites, for example, CO oxidation and that the effect of the support can be viewed as structural and electronic promotion. We identify the adsorption energy of oxygen and the Au-support interface energy as important parameters determining the catalytic activity.

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Section: The Importance Of the Au Coordination Numbermentioning

confidence: 92%

Section: The Importance Of the Au Coordination Numbermentioning

confidence: 99%

Section: Low Coordinated Au Atoms In Supported Au Catalystsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Insights into the reactivity of supported Au nanoparticles: combining theory and experiments

et al. 2007

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“…These properties have been related to changes in the electronic properties, the presence of defect sites, and the existence of strain for metallic gold nanoparticles. [4][5][6][7][8] Unique catalytic properties have also been related to the presence of sites associated with the catalyst support, such as cationic gold species, and sites at gold-support interfaces. [9,10] Here we show that it is possible to study the catalytic properties of metallic gold, without interference from a catalyst support, by using nanotubes of gold in polycarbonate membranes.…”

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confidence: 99%

Gold‐Nanotube Membranes for the Oxidation of CO at Gas–Water Interfaces

et al. 2004

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An exciting discovery in the area of heterogeneous catalysis is the observation that nanoparticles of gold on high-surfacearea supports exhibit high activity for oxidation of CO with O 2 (CO + 1/2 O 2 !CO 2 ) at room temperature. [1,2] This discovery is of particular relevance for the production of fuel-cell-grade hydrogen, since carbon monoxide must be removed from hydrogen streams generated by catalytic reforming of hydrocarbons.[3] The origins for the unique catalytic properties of supported gold catalysts are still unresolved. These properties have been related to changes in the electronic properties, the presence of defect sites, and the existence of strain for metallic gold nanoparticles. [4][5][6][7][8] Unique catalytic properties have also been related to the presence of sites associated with the catalyst support, such as cationic gold species, and sites at gold-support interfaces. [9,10] Here we show that it is possible to study the catalytic properties of metallic gold, without interference from a catalyst support, by using nanotubes of gold in polycarbonate membranes. These nanotubes exhibit catalytic activity for the oxidation of carbon monoxide by O 2 at room temperature, and this activity is enhanced by liquid water, promoted by increasing the pH of the solution, and increased using H 2 O 2 as the oxidizing agent. The rate can also be increased by depositing KOH within these nanotubes. These rates are comparable with those found in heterogeneous catalysis studies with gold nanoparticles on oxide supports, which suggests that the high activity of these latter catalysts may be related to the promotional effect of hydroxyl groups.Gold nanotubes of uniform size were prepared via a template-synthesis method by electroless deposition of gold [11] within the pores of a 10-mm-thick, track-etched polycarbonate membrane containing 220-nm-diameter pores.[12] All surfaces of the template membrane were first sensitized with a Sn II salt, activated by formation of a metallic Ag layer, followed by electroless deposition of gold for a period of 2 h. The gold nanotubes were cleaned with a 25 % HNO 3 solution for 15 h.[13] Hydrophobic or hydrophilic selfassembled monolayers were formed on gold nanotubes by rinsing the samples in ethanol for 20 min, followed by immersion for 17 h in solutions of ethanol containing HS(CH 2 ) 15 CH 3 or HS(CH 2 ) 15 COOH, respectively. [14] Gold nanotubes embedded within the pores of the polycarbonate template membranes were exposed by reactive ion etching (RIE) using an oxygen plasma to selectively etch approximately 2.3 mm of polycarbonate, leaving the gold nanotubes intact.[15] Figure 1 shows images from field-emission scanning electron microscopy (SEM) of the top surface of a template membrane after electroless deposition of gold followed by RIE. The images in Figure 1 reveal a high level of surface roughness; the length scale is % 53 nm. The membrane reactor used to study CO oxidation over gold nanotubes is shown schematically in Figure 2.[12] Table 1 shows results for the rate of...

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Nanocatalysis: Activation of Small Molecules and Conversion into Useful Feedstock

Kalidindi

Jagirdar

2013

Nanocatalysis Synthesis and Applications

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Untitled

Cited by 172 publications

References 25 publications

Insights into the reactivity of supported Au nanoparticles: combining theory and experiments

Insights into the reactivity of supported Au nanoparticles: combining theory and experiments

Gold‐Nanotube Membranes for the Oxidation of CO at Gas–Water Interfaces

Nanocatalysis: Activation of Small Molecules and Conversion into Useful Feedstock

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