Source of the catalytic activity of gold nanoparticles

Bond, Geoffrey C.

doi:10.1007/bf03214973

Cited by 29 publications

(27 citation statements)

References 16 publications

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“…The magnetic properties could provide the means to recover a catalyst, by applying a magnetic field, which could be used again. This prospect is especially interesting as Bond has recently reviewed that smaller particles reaching the non-magnetic state are more catalytically active [6]. This coincides with the trend towards magnetism for small particles with localized electrons (vide supra), and as such magnetism and catalytic properties might inherently go hand in hand.…”

Section: Outlook To Potential Industrial Applicationsmentioning

confidence: 67%

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Unexpected magnetism in gold nanostructures: making gold even more attractive

Trudel

2011

Gold Bull

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Gold nanostructures have attracted widespread attention due to their novel optical, electronic, and biocompatible properties. These make gold nanostructures (and in particular nanoparticles) very attractive for a variety of applications, including catalysis, therapeutics, diagnostics, sensing, and nanoelectronics. In this topical review, the newly discovered magnetic properties of gold nanostructures are highlighted. This unexpected magnetism in gold nanoparticles is a result of (1) the predominant effect of surfaces at the nanoscale, (2) the electronic modification to gold from strongly capping molecules, and (3) the strong spin-orbit coupling of gold. This review discusses the salient experimental results, a theoretical model, and closes by highlighting possible industrial applications of magnetic gold nanostructures.

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Section: Outlook To Potential Industrial Applicationsmentioning

confidence: 67%

“…Ever since the pioneering work of Brust [1], gold (Au) nanoparticles have been a focus of interest due to their novel optical, electronic, catalytic, sensing, and biomedical applications [2][3][4][5][6][7][8]. The development of gold nanoparticle synthesis has led to a renaissance of gold chemistry [9].…”

Section: Introductionmentioning

confidence: 99%

Unexpected magnetism in gold nanostructures: making gold even more attractive

Trudel

2011

Gold Bull

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“…The increase of the activity of Au/ CeO 2 (rod)-CN upon reduction underpins the notion that reduced gold atoms are beneficial for CO oxidation. On the other hand, the high activity appears also to be correlated to the ability of the small gold clusters in Au/CeO 2 (rod)-CN to be reoxidized [77]. The observation that part of the high activity of Au/CeO 2 (rod) is lost may point to the loss of finely dispersed gold clusters due to agglomeration with the larger nanoparticles.…”

Section: Discussionmentioning

confidence: 95%

Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

et al. 2011

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The interaction of gold atoms with CeO 2 nanocrystals having rod and cube shapes has been examined by cyanide leaching, TEM, TPR, CO IR and X-ray absorption spectroscopy. After deposition-precipitation and calcination of gold, these surfaces contain gold nanoparticles in the range 2-6 nm. For the ceria nanorods, a substantial amount of gold is present as cations that replace Ce ions in the surface as follows from their first and second coordination shells of oxygen and cerium by EXAFS analysis. These cations are stable against cyanide leaching in contrast to gold nanoparticles. Upon reduction the isolated Au atoms form finely dispersed metal clusters with a high activity in CO oxidation, the WGS reaction and 1,3-butadiene hydrogenation. By analogy with the very low activity of reduced gold nanoparticles on ceria nanocubes exposing the {100} surface plane, it is inferred that the gold nanoparticles on the ceria nanorod surface also have a low activity in such reactions. Although the finely dispersed Au clusters are thermally stable up to quite high temperature in line with earlier findings (Y. Guan and E. J. M. Hensen, Phys Chem Chem Phys 11:9578, 2009), the presence of gold nanoparticles results in their more facile agglomeration, especially in the presence of water (e.g., WGS conditions). For liquid phase alcohol oxidation, metallic gold nanoparticles are the active sites. In the absence of a base, the O-H bond cleavage appears to be rate limiting, while this shifts to C-H bond activation after addition of NaOH. In the latter case, the gold nanoparticles on the surface of ceria nanocubes are much more active than those on the surface of nanorod ceria.

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“…To date the highest H2 storage capacity was reported in the case of metal hydrides 12 and noble 50 metals (such as Pd, or Au). Although H2 adsorption on gold surfaces was demonstrated to be weaker than on palladium (up to 900 times its volume of hydrogen 13 ), gold catalytic activity was shown to be enhanced for gold NPs 14,15 . The presence of gold NPs on GaN nanowires 16 was found to change the sensing capacity of the bare nanowires.…”

Section: A Introductionmentioning

confidence: 99%

“…The critical limitation of their development remains so far the processing and exposure of large surface areas of metallic NPs within highly porous matrices composed of a naturally high 60 specific surface area material to optimize the surface to volume ratio. sensitive to selective gas adsorption 14,26 . The oxidation of CO by various sizes of gold NPs was found to be up to 100 times higher with sub 2 nm…”

Section: A Introductionmentioning

confidence: 99%

Activation of gold decorated carbon nanotube hybrids for targeted gas adsorption and enhanced catalytic oxidation

et al. 2012

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10Free standing assemblies of carbon nanotubes (CNTs), known as bucky-paper, (BP) have been functionalised through the in-situ plating of gold nanoparticles within the interstitial spaces in the BP. The nanoparticles are extremely small and well distributed at short plating times, so much so that the specific surface area of the BP is actually 15 increased by the gold incorporation. These well distributed nanoparticles exhibit high enthalpy hydrogen storage and selective carbon dioxide adsorption over other gases, in particular methane. In concert with the conductive BP substrate, it has been demonstrated that these materials can also act as high turnover heterogeneous catalysts. (Graphical abstract)Keywords 25 gold decorated carbon nanotube; composite bucky-paper; specific gas storage; catalytic activity Self-supporting BPs were processed from chemical vapour deposition grown multi walled CNTs as described in a previous study 51 . Research highlightsIn short, the functionalized CNTs were then suspended in propan-2-ol by 5 repeated cycles of freezing at -17 ºC followed by bath sonication as per the method developed in 50 . The CNT suspension was then filtered on top 10 of a porous poly(ether sulphone) membrane to form a self-supporting BP.BPs were exposed for 10 min to a flow of UV induced ozone in order to form hydroxyl groups at the surface of outer CNT walls 52, 53 . These groups are needed to both facilitate wetting of the CNTs by the plating solutions and as anchors for the initial plating reactions. 15The procedure of electroless gold deposition within porous materials has been described by Martin et al. 54 and was previously used to fabricate pure gold nanotubes 48 in a three step protocol. During the first step, BP properties analysisThe gold content in the structure was determined by Thermo Scanning Electron Micrographs (SEM) at 5 keV, 52 º of tilt and 5 cm working distance. The Gallium (Ga) milling was performed with an initial beam current of 7 nA followed by cleaning steps at 0.1 nA. Eventually, pore size distribution was determined by perm-porometry on a capillary flow porometer from Porous Materials Inc. in wet-up/dry-up mode. 50Galwick and N2 were respectively used as the wetting liquid and to pressurize the BP pores up to 500 psi. Gas adsorptionThe adsorption of N2, CH4 and CO2 was performed at room Catalytic activity determinationBPs were exposed to pure analytical grade pentanal at 70 ºC in oxygenated CDCl3 for times of either 2 or 24 h. The composition of the solution before and after being exposed to the catalytic influence of the 65 BPs were analysed using Nuclear Magnetic Resonance (NMR) on aBruker 400 MHz spectrometer. TGA performed on the series of samples showed an initial diminished thermal stability which was attributed to the ozone treatment inducing defects on the CNT walls. However, after 10 h of plating the 90 stability, compared to a non treated sample, was recovered and improved. C. Results and DiscussionThe samples were all stable up to 400 ºC. The gold content c...

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Source of the catalytic activity of gold nanoparticles

Cited by 29 publications

References 16 publications

Unexpected magnetism in gold nanostructures: making gold even more attractive

Unexpected magnetism in gold nanostructures: making gold even more attractive

Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

Activation of gold decorated carbon nanotube hybrids for targeted gas adsorption and enhanced catalytic oxidation

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