In Situ Attenuated Total Reflection Infrared Spectroscopy of Dendrimer-Stabilized Platinum Nanoparticles Adsorbed on Alumina

Liu, Dongxia; Gao, Junyuan; Murphy, Catherine J.; Williams, Christopher T.

doi:10.1021/jp048879i

Cited by 51 publications

(58 citation statements)

References 44 publications

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“…The supported DENs were active for CO oxidation in water and showed activity comparable to a Pt/Alumina catalyst prepared via wetness impregnation of H 2 PtCl 6 . This study also showed that the presence of the Pt nanoparticle has a substantial effect on the stretching frequencies associated with the amide bonds that make up the dendrimer backbone [81] .…”

Section: Den Deposition Onto Oxide Supportsmentioning

confidence: 54%

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PAMAM Dendrimer Templated Nanoparticle Catalysts

Chandler

Gilbertson

2007

Nanoparticles and Catalysis

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Section: Den Deposition Onto Oxide Supportsmentioning

confidence: 54%

“…Presumably, upon drying, the organic dendrimer collapses onto the nanoparticle, poisoning the metal surface [80,81] . The activity of immobilized DEN electrocatalysts in water and a study by Williams and coworkers have provided the strongest evidence in support of dendrimer poisoning of supported dried DENs.…”

Section: Den Deposition Onto Oxide Supportsmentioning

confidence: 99%

PAMAM Dendrimer Templated Nanoparticle Catalysts

Chandler

Gilbertson

2007

Nanoparticles and Catalysis

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“…These observations suggest that PAA is partly removed from the Pt surface by the competitive adsorption of hydrogen in the presence of solvent, whereas this process is not possible at the solid/gas interface during CO chemisorption. Dendrimer-encapsulated nanoparticles showed a similar behavior of reasonable activity in the presence of a solvent, [68,69] although they were inactive for gas-phase reactions. [70] Boudart and co-workers [67] demonstrated that cyclohexene hydrogenation on Pt is structure-insensitive, independent of the catalyst support, metal loading, and particle size.…”

Section: Catalytic Behavior Of the Nanoparticlesmentioning

confidence: 95%

Platinum Nanoparticles: The Crucial Role of Crystal Face and Colloid Stabilizer in the Diastereoselective Hydrogenation of Cinchonidine

Schmidt

Kleist

Krumeich

et al. 2010

Chemistry A European J

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The preparation of stable metal nanoparticles requires a strong interaction between the (organic) stabilizer and the metal surface that might alter the catalytic properties. This behavior has been described as "poisoning" since the stabilizer normally decreases the catalytic activity due to site blocking. Here we show a striking influence of the stabilizer on the selectivity in the hydrogenation of cinchonidine (CD) over poly(acrylic acid) (PAA)-stabilized Pt nanoparticles with well-defined shape distributions. In the hydrogenation of the heteroaromatic ring of cinchonidine in toluene, the diastereomeric excess of the (S)-hexahydrocinchonidine increased upon increasing Pt{111}/Pt{100} ratio, but this distinct shape selectivity was observed only after the oxidative removal of PAA at 473 K. The use of the as-prepared nanoparticles inverted the major diastereomer to R, and this isomer was formed also in acetic acid. This striking change in the diastereoselectivity indicates that poly(acrylic acid), which remains on the Pt surface after preparation, interacts with CD during hydrogenation almost as strongly as the solvent acetic acid. The PAA stabilizer plays a dual role: it allows one to control the size and shape of the nanoparticles during their synthesis, and it affects the rate and diastereoselectivity of the hydrogenation of CD probably through a "surface-localized acidification".

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“…For example, for Pt nanoparticles, stabilized by dendrimers, large peak widths of ϳ50 cm −1 are found for CO adsorption with liquid phase ATR infrared spectroscopy. 12 In addition, a distribution in the particle size may also cause a wider absorption peak. For example, for Au particles, a shift of 7 cm −1 to higher wave numbers for increasing particle size, corresponding to a coverage increase from 0.5 to 20 monolayers of Au, is reported for CO adsorption.…”

Section: Discussionmentioning

confidence: 99%

“…Many applications are found in the literature for surface science studies 8,9 and liquid phase surface adsorption studies. [10][11][12][13][14][15] Other applications are found for studies on, e.g., thin ͑nano͒crystalline and amorphous silicon films and surfaces. [16][17][18] Moreover, gas phase adsorption of precursors on a very thin metallic layer of TiCN on a Si ATR crystal, in combination with hydrogen diffusion through this layer, has been studied.…”

Section: Introductionmentioning

confidence: 99%

Attenuated total reflection infrared spectroscopy for studying adsorbates on planar model catalysts: CO adsorption on silica supported Rh nanoparticles

Leewis

Kessels

Sanden

et al. 2006

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. A sensitive method is presented for studying adsorption of gaseous species on metal surfaces in vacuum by attenuated total internal reflection Fourier transform infrared spectroscopy ͑ATR͒. The method is illustrated by CO adsorption experiments on silica supported Rh nanoparticles. An experimental setup and a procedure are described in detail to obtain a sensitivity of reflectance change of ϳ5 ϫ 10 −5 absorbance units. Here, a silicon ATR crystal with a 50 nm layer of hydroxylated silica acts as the support for the Rh nanoparticles. These particles are easily prepared by spincoat impregnation from a RhCl 3 solution followed by H 2 reduction. X-ray photoelectron spectroscopy before and after reduction shows that rhodium is reduced to Rh 0 and that all chlorine is removed. Atomic force microscope images the distribution of the particles, which are 3 -4 nm in height. When the crystal is exposed to pressures up to 1 mbar of CO, a gas which is inert to the silica support, the stretch vibration of linearly adsorbed CO on the Rh nanoparticles is detected at 2023 cm −1 , while no bridged CO or geminal dicarbonyl species can be distinguished. The minimum detectable coverage is estimated ϳ0.005 CO per nm 2 substrate area or ϳ5 ϫ 10 −4 ML.

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In Situ Attenuated Total Reflection Infrared Spectroscopy of Dendrimer-Stabilized Platinum Nanoparticles Adsorbed on Alumina

Cited by 51 publications

References 44 publications

PAMAM Dendrimer Templated Nanoparticle Catalysts

PAMAM Dendrimer Templated Nanoparticle Catalysts

Platinum Nanoparticles: The Crucial Role of Crystal Face and Colloid Stabilizer in the Diastereoselective Hydrogenation of Cinchonidine

Attenuated total reflection infrared spectroscopy for studying adsorbates on planar model catalysts: CO adsorption on silica supported Rh nanoparticles

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