Immobilization nanoparticles

Figure 16. Scanning electron micrograph of a pair of nanoelectrodes with gold nanoparticles immobilized into the gap using a mixture of large particles small particles derivatized with RNA phosphate buffer containing NaCl in the presence of Mg. (Reprinted with permission from Ref [31], 2006, American Chemical Society.)...

Si-C formation technique with hydrogen-terminated silicon substrates can also be used as the covalent attachment of nanomaterials onto silicon surface. The possibility of assembling nanomaterials in order is strongly desired in order to enable efficient utilization of their unique nano-sized properties. Ordered arranging and position controlling of nanomaterials on solid substrates especially on silicon surface have been intensively studied [10]. In this manuscript, the nanoparticle immobilization by thermal Si-C formation will be discussed [11]. 

Gold nanoparticles can be clearly observed as white dots and silicon wafers are black in HR-SEM images of the gold nanoparticles-immobilized silicon surface. When immobilizing the allylthiol (C3, HS-CHj-CH = CHj)-stabilized gold nanoparticles, even the reaction temperature was as low as 50 °C, the white dots with diameters about lO Onm are observed (Figure 5A). 

Phenylation of styrene, acrylic esters, and acrylamide with Ph3Bi(02CCF3)2 was examined using palladium nanoparticles immobilized in spherical polyelectrolyte brushes (Pd SPB) (Scheme 7) [21], The reaction can be conducted under air, and... 

Miyake M, Torimoto T, Sakata T, Mori H, Yoneyama H (1999) Photoelectrochemical characterization of nearly monodispersed CdS nanoparticles-immobilized gold electrode. Langmuir 15 1503-1507 Torimoto T, Tsumura N, Miyake M, Nishizawa M, Sakata T, Moii H, Yoneyama H (1999) Preparation and photoelectrochemical properties two dimensionally organized CdS nanoparticle thin films. Langmuir 15 1853-1858... 

RuCNC heterobi metal lie ruthenium/cobalt nanoparticle immobilized on charcoal. 2-Pyridylmethyl formate is used. 

Highly dispersed palladium nanoparticles immobilized on alumina were prepared via the sonochemical reduction by alcohols of Pd(II).366 The activity of these catalysts was 3-7 times higher in the hydrogenation of alkenes than that of conventional catalysts, and they showed a high preference to hydrogenate 1-hexene over trans-3-hexene. 

Thus, the size effects for catalytic reactions of metal atom clusters in a gas phase are manifested only in very small, essentially quantum clusters, which are in essence nonmetal particles. Another situation takes place in films, containing a set of nanoparticles immobilized at a surface or inside of a dielectric matrix. In this case the influence of M nanoparticle size on catalytic activity and structure of products formed is observed for considerably larger already classical particles of sizes from 2 ( 150 atoms) to 20-30 nm ( 105 atoms) [113, 114]. It is necessary to note that catalytic properties of M nanoparticles in composite systems are determined substantially by their interaction with a matrix, which depends on the size of particles. 

Specific catalytic properties of synthesized Pd-PPX nanocomposites have been explained by the tunnel charge transfer between nanoparticles. As mentioned in Section 2, the energy of Fermi level of small metal particle depends on its size [14], At the same time, M nanoparticles immobilized in PPX matrix have rather wide size distribution in the range 2-8 nm (Section 3). Electron transfer between particles of different size results in their mutual charging that leads to equalization of their electrochemical potentials [15],... 

Originally, the effect of charge state of nanostructures on their catalytic activity was recognized from analysis of the experimental data on the catalytic properties of metallic nanoparticles immobilized in the matrix of a poly-paraxylylene polymer [13-15,24]. It was found that the dependence of the catalytic activity (and, in some cases, of the selectivity) of copper, palladium, and iron nanoparticles on the metal content of these structures has a maximum. This maximum exists not only for the specific (related to unit weight) activity, but also for the absolute activity. More specifically, for copper and... 

Yang W, Li Y, Bai Y, Sun C (2006) Hydrogen peroxide biosensor based on myoglobin/ colloidal gold nanoparticles immobilized on glassy carbon electrode by a Nafion film. Sens Actuators B 115 42—48... 

Yang, W. W., Bai, Y., Li, Y. C. and Sun, C. Q. (2005a), Amperometric nitrite sensor based on hemoglobin/colloidal gold nanoparticles immobilized on a glassy carbon electrode by a titania sol-gel film. Anal. Bioanal. Chem., 382(1) 44-50. 

More recently this group has prepared a combination of palladium and cobalt nanoparticles immobilized on silica (PCNS) to form bicyclic enones after domino allylic alkylation-PKR [130]. 

Following their works on immobilized heterobimetallic nanoparticle catalysts, Chung s group has synthesized Ru/Co nanoparticles immobilized in charcoal and shown the ability of this system to catalyze a PKR-type reaction in the presence of pyridylmethyl formiate as a CO source. They used these conditions with intra- and intermolecular reactions and showed that the catalyst can be reused without loss of catalytic activity (Scheme 40) [146]. 

The catalytic activity of Ag/Pd bimetallic nanoparticles immobilized on quartz surfaces was tested for 4-nitro-3-pyrazole carboxylic acid with help from surface plasmon resonance, scanning electron microscopy, and surface-enhanced Raman scattering (SERS) measurements [1417], The SERS spectra showed that the nitro group reduces to amino group. 

Fig. 3 Formation of metal nanoparticles in the PS-PNIPA core-shell system. The crosslinked PNIPA chains absorb metal ions step 1) which are reduced to produce corresponding metal nanoparticles immobilized in the thermosensitive network step 2)...

Figure 10 shows the values of the apparent rate constant kapp as a function of theoretical specific surface area of metal nanoparticles immobilized in different carrier systems. As shown in Fig. 10, a strictly linear relationship between kapp and the surface of the metal nanoparticles can be observed. Figure 10 demonstrates that Pt and Pd nanoparticles exhibit higher catalytic activity than AgNPs. Table 1... 

Fig. 14 Catalytic oxidation of benzyl alcohol in the presence of metal nanoparticles immobilized in thermosensitive core-shell microgels at different temperatures. At lower temperatures (T < 32°C) the microgel network is hydrophilic and swollen in water, whereas at high temperatures (T > 32°C), the network shrinks and becomes hydrophobic. Thus, microgel particles embedding the metal catalyst will move to the oil phase, which will be favorable for the uptake of hydrophobic benzyl alcohol into the metal-microgel composite. Therefore, the catalytic activity of the metal-microgel composites will be affected both by the volume transition and the polarity change of the microgel [29]...

Malysheva YB, Gushchin AV, Mei Y, Lu Y, Ballauff M, Proch S, Kempe R (2008) C-C coupling reaction of triphenylbismuth(V) derivatives and olefins in the presence of palladium nanoparticles immobilized in spherical polyelectrolyte brushes. Eur J Inorg Chem 3 379-383... 

Mei Y, Sharma G, Lu Y, Drechsler M, Ballauff M, Irrgang T, Kempe R (2005) High catalytic activity of platinum nanoparticles immobilized on spherical polyelectrolyte brushes. Langmuir 21 12229-12234... 

Rooney P, Rezaee A, Xu S et al (2008) Control of surface plasmon resonances in dielectrically-coated proximate gold nanoparticles immobilized on a substrate. Phys Rev B 77 235446... 

Figure 4.5 (A) Darkfield optical micrograph of a typical distribution of single Ag nanoparticles immobilized on a glass cover slip. (B) Single-particle darkfield scattering spectra corresponding to the individual Ag nanoprisms labeled in (A). The ensemble solution extinction spectrum is shown as the shaded, dashed curve for comparison. Reprinted with permission from reference 9.

Figure 4.5 (A) Darkfield optical micrograph of a typical distribution of single Ag nanoparticles immobilized on a glass cover slip. (See text for full caption.)...

Driskell JD, Lipert RJ, Porter MD (2006) Labeled gold nanoparticles immobilized at smooth metallic substrates systematic investigation of surface plasmon resonance and surface-enhanced Raman scattering. J Phys Chem B 110 17444—17451... 

SERS from Metal Nanoparticles Immobilized on Optically Trapped Beads... 

S. Naskar, S. A. Pillay, M. Chanda, Photocatalytic degradation of organic dyes in aqueous solution with Ti02 nanoparticles immobilized on foamed polyethylene sheet , Journal of Photochemistry and Photobiology A Chemistry, 113, 257-264, (1998). 

Miyake, M., T. Torimoto, T. Sakata, H. Mori, and H. Yoneyama, Photoelectrochemical characterization of nearly monodisperse CdS nanoparticles-immobilized gold electrodes. Langmuir, 1999. 15 pp. 1503-1507... 

Cattech highlights (1997) Zeolites and chirality, Cattech, 1,149-151. Mastalir, A., Szollosi, G., Kiraly, Z., Razga, Z. (2002) Preparation and characterization of platinum nanoparticles immobilized in dihydrocin-chonidine-modified montmorillonite and hectorite, /i/i/. Clay Sci. 22,9-16. Gross, L.H., Rys, P. (1974) Heterogeneous catalytic asymmetric hydrogenation, J. Org. Chem. 39, 2429-2430. 

For the sample PPX -f Cu the calculated fractal dimension Df is equal to 2.609 [70]. It should be noted that the above-mentioned size distribution of metal nanoparticles leads to the mutual charging of such particles in the percolation cluster. This effect is discussed in the following section in coimection with catalysis by nanoparticles. As stated in reference 70, the specific low-temperature peak of dielectric losses in the synthesized composite samples PPX -t-Cu is probably due to the interaction of electromagnetic field with mutually charged Cu nanoparticles immobilized in the PPX matrix. The minor appearance of this peak in PPX -i- Zn can be explained by oxidation of Zn nanoparticles. 

Recently, there have been many reports on the effects of CD on metal catalytic systems. A potentially interesting approach for the modification of catalytic systems based on metal complexes, such as Zn, Mo, Fe, In, Sn, Pd or Ru, involves the use of CD as a protective agent. There are many reports on the interaction between CDs and metallic nanoparticles.Immobilized CD on Pd nanoparticles was employed as an efficient mediator in aqueous biphasic hydrogenation reactions (Figure 4.6a,b). ... 

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