Composites nanoparticle

In 2000, Sun and co-workers succeeded in synthesis of monodispersed Fe/Pt nanoparticles by the reduction of platinum acetylacetonate and decomposition of Fe(CO)5 in the presence of oleic acid and oleylamine stabilizers [18]. The Fe/Pt nanoparticle composition is readily controlled, and the size is tunable from 3 to 10 nm in diameter with a standard deviation of less than 5%. For practical use, we developed the novel symthetic method of FePt nanoparticles by the polyol reduction of platinum acetylacetonate (Pt(acac)2) and iron acetylacetonate (Fe(acac)3) in the presence of oleic acid and oleylamine stabilizers in di- -octylether [19,20]. The Fe contents in FePt nanoparticles can be tuned from 23 to 67atomic%, and the particle sizes are not significantly affected by the compositions, retaining to be 3.1 nm with a very narrow size distribution, as shown in Figure 6. 

The emission properties of QDs can be adjusted based upon core diameter and nanoparticle composition. Nanoparticle diameters typically are carefully controlled during manufacture to be between 2 and 10 nm. In addition, the band gap energy or energy of fluorescence emission is inversely proportional to the diameter of the QD particle. Thus, the smaller the particle, the... 

Similar Suzuki couplings have been performed by Hu and coworkers utilizing a poly(dicyclohexylcarbodiimide)/palladium nanoparticle composite [152]. This PDHC-Pd catalyst showed remarkable activity and stability under microwave irradiation. Near quantitative conversion (95% isolated yield) was obtained after 40 min of microwave heating of a mixture of iodobenzene with phenylboronic acid in dioxane. Re-using the immobilized catalyzed showed no significant loss of efficiency, as the fifth cycle still furnished a 90% isolated yield of the desired biphenyl. 

B. Kim and W.M. Sigmund, Functionalized multiwall carbon nanotube/gold nanoparticle composites. Langmuir 20, 8239-8242 (2004). 

Suzuki, D. Kawaguchi, H., Modification of gold nanoparticle composite nanostructures using thermosensitive core shell particles as a template, Langmuir. 2005, 21, 8175 8179... 

Guan H, Zhou P, Zho X, He Z (2008) Sensitive and selective detection of aspartic acid and glutamic acid based on polythiophene-gold nanoparticles composite. Talanta 77 319-324... 

Narayanan, R., M. Deepa, and A.K. Srivastava, Nanoscale connectivity in a Ti02/CdSe quantum dots/functionalized graphene oxide nanosheets/Au nanoparticles composite for enhanced photoelectrochemical solar cell performance. Physical Chemistry Chemical Physics, 2012.14(2) p. 767-778. 

Hu, X., et ah, A general route to prepare one- and three-dimensional carbon nanotube/metal nanoparticle composite nanostructures, hangmuir, 2007. 23(11) p. 6352-6357. 

Tjoa, V., et al., Facile photochemical synthesis ofgraphene-Pt nanoparticle composite for counter electrode in dye sensitized solar cell. ACS Applied Materials Interfaces, 2012. 

Poudel, P. Qiao, Q., One dimensional nanostructure/nanoparticle composites as photoanodes for dye-sensitized solar cells. Nanoscale 2012,4 2826-2838. 

CNTs-nanoparticles composites have also been exploited for electrochemical sensing applications [17, 118, 119[. Incorporation of metal and oxide nanoparticles has been demonstrated to enhance the electrocatalytical efficiency. A wide range of particles have been used (Pt, Pd, Co, FeCo alloy, Co, Cu, Ag, Cu) and in some cases such CNT/nanoparticles have been combined together with charged polymers [17]. 

Fig. 9.16 a) Schematic outline of the consecutive built-up of SAM/nanoparticle composites by means of charge interactions. Three different bis-benzamidines were used to serve as a linking layer, variing their alkyl chain... 

Srivastava S, Verma A, Frankamp BL, Rotello VM. Controlled assembly of protein-nanoparticle composites through protein surface recognition. Adv Mater 2005 17 617-621. 

Figure 6.5 (a) The formation of ferritin-mediated self-assembly of FePt nanoparticles via electrostatic interactions, (b) magnetic dipole-dipole interaction of ferritins assembled with FePt nanoparticles, and (c) zero field cooling and field cooling results for the ferritin-FePt nanoparticle composite film and individual components. Reprinted with permission from Srivastava, Samanta, Jordan, et al. (2007). Copyright 2007 American Chemical Society. 

Sun, H., Direct electrochemical and electrocatalytic properties of heme protein immobilized on ionic liquid-clay-nanoparticle-composite films,/. Porous Mater., 13, 303-397,2006. 

Scheme 3.20 Dendrimer-gold nanoparticle composite prepared from G5-PAMAM dendrimer and Au NPs bearing —COOH groups.

RDX) Bisaniline-cross-linked gold nanoparticles composite LOD 4 nM [43]... 

Figure 13.3 The LbL assembly of negatively charged CdS and Ti02 nanoparticles, and positively charged polyelectrolytes to form nanoparticle-composite films, 26...

UV-visible spectra of nanoparticles arise from two sources. The first, more general source is simple Rayleigh scattering that gives rise to the monotonic increase in absorption as wavelength decreases [33]. Au and Ag nanoparticles have intense surface plasmon bands that are valuable additional spectroscopic tools [33-35]. These bands, which arise from a concerted oscillation of nanoparticle electrons, shift with particle size and composition, and are therefore useful handles for the physical characterization of nanoparticle composition. 

Water-solubilized aminoclay-metal nanoparticle composites and their novel properties... 

In the present study the property of the aminociays wherein protonation of the amino groups in water is accompanied by exfoliation has been exploited.15 Thus metal nanoparticle composites formed by the exfoliated aminoclay sheets by carrying out the reduction of metal precursors in the presence of the clay have been investigated. Besides being entirely water soluble, the exfoliated sheets of aminoclay-Au nanoparticle composites move to the organic/aqueous interface in the presence of an alkanethiol. 

Fig. 2 Optical images of aminoday-metal nanoparticle composites forming clear transparent solutions in water (a) aminoclay solution, and aminoclay with (b) Au, (c) Ag, (d) Pt and (e) Pd nitnopartides.

Fig. 2 shows how the aminoday -metal nanoparticle composites form clear transparent solutions in water. The solutions are pink and yellow for Au and Ag respectively and dark brown in the cases of both Pt and Pd. The reddish-brown colour observed for Au-clay nanoparticle composites immediately after the addition of NaBH4 changed to pink with time. The solutions exhibit characteristic piasmon bands for the Au- and Ag-day suspensions at 520 nm and 410 nm respectively as shown in Fig. 3. In the cases of Pt and Pd, the characteristic absorption band for the precursor s around 260 to 280 nm was absent thereby confirming the formation of Pt and Pd nanoparticles. 7,18 TEM images of the aminoday-metal nanoparticle composites deposited on a carbon coated copper grid are shown in Fig. 4. The histograms show the average particle sizes to be around 3.5 and 5 nm respectively in the cases of Au and Ag nanoparticles. We could see the layered arrangements in the cases of Pt and Pd with the interspacing of 1.5 nm commensurate with the bilayer arrangement of aminoclays (see top right inset of Fig. 4b).

The aminoday Au nanoparticle composite was also prepared by an in-situ procedure, wherein the reduction was carried out thermally without the use of NaBH4. The clay composite so prepared also dissolves in water and shows the characteristic piasmon band at 530 nm. 

Fig. 4 TEM images of (a) Ail-clay nanoparticle composites. Inset histogram of Au nanopartides (b) Ag-clay nanopartides composite. Insets (bottom left) histogram of Ag nanopartides (top right) Pt nanopartides show layered arrangement.

Keywords. Polymer latex, Miniemulsion, Heterophase polymerization, Polymer nanoparticles, Composite particles... 

Murugadoss, A. and Chattopadhyay, A. 2008. A green chitosan-silver nanoparticle composite as a heterogeneous as well as micro-heterogeneous catalyst Nanotechnology, 19 9. 

Ferritin induced nanoparticle synthesis was adapted from a number of different synthetic strategies reliant upon the physical nature of ferritin. For instance, ferritin can readily exist in two stable forms (native ferritin with an intact iron oxide core or apo-ferritin lacking a mineral core) owing to the enhanced structural integrity of the protein shell. As a result, two general reaction schemes were adopted. The first route utilized the iron oxide core of native or reconstituted ferritin as a precursor to different mineral phases and types of iron nanoparticles, while the second invokes mineralization within the empty cavity of apo-ferritin. In the latter approach, the native protein must be demetallated by reductive dissolution with thioglycolic acid to yield apo-ferritin. Ultimately, apo-ferritin provides a widely applicable means to the synthesis of various nanoparticle compositions under many conditions. 

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