Encapsulated platinum nanoparticles

For the applicability of these polymer-stabilized water-soluble nanoparticles in catalysis, the hydrogenation of olefins (i.e., isophorone) with the hyperbranched PEI-GLU-encapsulated platinum nanoparticles was investi-... 

X.L., and Li, C.Z. (2007) Amperometric glutamate biosensor based on selfassembling glutamate dehydrogenase and dendrimer-encapsulated platinum nanoparticles onto carbon nanombes. Talanta, 73, 438 43. 

PAMAM Dendrimer-Platinum Conjugates and Applications 2.1 PAMAM Dendrimer-Encapsulated Platinum Nanoparticles... 

Albiter MA, Crooks RM, Zaera F (2010) Adsorption of carbon monoxide on dendrimer-encapsulated platinum nanoparticles liquid versus gas phase. J Phys Chem Lett 1 38... 

Zhao et al (70) developed a method for the synthesis of dendrimer-encapsulated metal nanoparticles based on sorbing metal ions into (modified) PAMAM dendrimers followed by a reduction. Dendrimers encapsulating copper, palladium, and platinum nanoparticles have been prepared. Hydroxyl-terminated PAMAM dendrimers were used to prepare encapsulated palladium (PAMAM generations 4, 6, and 8) and platinum (PAMAM generations 4 and 6) nanoparticles. The dendrimer-encapsulated palladium and platinum nanocomposites catalyzed the hydrogenation reaction of allyl alcohol and N-isopropyl acrylamide in water 71). 

While they are not strictly redox-containing dendrimers. Crooks and Zhao have encapsulated platinum and other metallic nanoparticles inside PAMAM dendrimers. The catalytic properties of these materials have been examined using cyclic voltammetry, and it was found that a gold electrode, modified with large hydroxyl-terminated PAMAM dendrimers containing clusters of 60 platinum atoms, was readily able to catalyze O2 reduction [98]. Similar results have been reported for palladium clusters encapsulated in the same hydroxyl-terminated PAMAM dendrimers [99]. 

Dendrimer-encapsulated nanoparticles have potential applications in the energy sector. For example, polyamidoamine (PAMAM) dendrimer-encapsulated platinum nanoparlicles (Pt-DENs) have been introduced as a promising cathode catalyst for air-cathode single-chamber microbial fuel cells (SCMFCs) [64], This novel catalyst led to higher power production with 129.1%, as compared to cathodes with electrodeposited Pt. 

Palladium and Platinum. PHIP has been used to study the hydrogenation of phenyl acetylene by colloidal palladium.In situ P NMR spectroscopy has been used to show the resting state of the [(Pr 2PCH2CH2CH2PPr 2)Pd(PR3)2] in the catalysis of the reaction of ethene with The size-selective hydrogenation of alkenes by dendrimer-encapsulated palladium nanoparticles has been investigated by NMR spectroscopy. 

San BH, Kim S, Moh SH, Lee H, Jung DY, Kim KK (2011) Platinum nanoparticles encapsulated by aminopeptidase a multifunctional bioinorganic nanohybrid catalyst. Angew Chem Int Ed Engl 50 11924-11929... 

Ishino S, Harada T, Okamoto N, Sakata T, Mori H, Kuwabata S, Torimoto T, Matsumura M, Ikeda S (2006) Ligand-free platinum nanoparticles encapsulated in a hollow porous carbon shell as a highly active heterogeneous hydrogenation catalyst. Angew Chem Int Ed 45 ... 

BASF is industrially producing MOF-5 mainly for encapsulating platinum, palladium, copper, and gold nanoparticles for catalysis applications. The Pd MOF-5 is used as a heterogeneous catalyst in hydrogenation reactions, specifically hydrogenation of cyclooctene, while Cu MOF-5 is used in methanol production from syngas [80]. 

Fig. 7.4 (a) Carbon spheres loaded with silver nanoparticles at room temperature (b) carbon spheres loaded with palladium nanoparticles by refluxing (c) silver core of carbon spheres from encapsulation of silver nanoparticle seeds, (d) layered structure with an silver core, a platinum shell, and a carbon interlayer, formed by seeded encapsulation followed by the reflux method. 

In contrast to standard borohydride reductive nanoparticle synthesis, we have developed an alternative strategy to amino acid encapsulated nanoparticles by utilizing a metal nanoparticle (M°-(Ligand))/metal ion (M"+) precursor redox pair with matched oxidation/reduction potentials. Simply, a metal nanoparticle such as Pt°-(Cys) acts as the principal reductant to a complimentary selected metal ion of Au + resulting in a new stabilized metal nanoparticle of Au°-(Cys) and the oxidation product of the original nanoparticle Pt"+. Malow et al. have reported a metathesis/transmetallation type reaction between a platinum colloid and a Au cyanide compound. Similarly, we employed a Pt°-(Cys)/AuCl4 pair and 0.5-2.0 equivalents of Au to Pt -(Cys). XRD analysis of the nanoparticle products revealed differences in crystallinity... 

Tsang et al. [26] described the use of Ft nanoparticles (average size 5nm) encapsulated in porous silica aerogel coating (5% of metal), and then deposited on conventional y-alumina as a composite catalyst for butane oxidation (Fig. 5.6). Preparation of the material was carried out from a microemulsion obtained by using ammonium tetrachloroplatinate(ll), cetyltrimethylamonium bromide in a toluene/water mixture, and then the reduction of platinum anion was accom-... 

Dendrimer-encapstdated catalysts are another area of active research for polymer-supported catalysts. The nanoparticles are stabilized by the dendrimers preventing precipitation and a omeration. Bimetallic nanoparticles with encapsulated metals (dendrimer-encapsulated catalyst DEC) from commercially available fourth-generation PAMAM dendrimers and palladium and platinum metal salts were prepared via reduction by Crooks and co-workers [34], following previous work in this area [35], The simultaneous incorporation of Pt and Pd reflects the concentrations in solution. The bimetallic DECs are more active than the physical mixture of single-metal DEC [35, 36] in the case of the hydrogenahon of allyl alcohol in water, with a maximum TOP of 230 h compared to TOP = 190 h obtained for monometallic palladium nanoparticles (platinum TOP = 50 h ). 

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