Nanoparticle size

Ebenstein, Y., Nahum, E., and Banin, U., Tapping mode atomic force microscopy for nanoparticle sizing Tip-sample interaction effects, Nano Lett., 2, 945, 2002. 

A study of the effect of magnetic nanoparticle size on the monolayer behavior aimed to examine the balance between magnetic dipole forces and van der Waals interactions... 

Some investigations have emphasized the importance of micellar size as a control parameter of nanoparticle size [224]. It has been suggested that other factors also influence the nanoparticle size, such as the concentration of the reagents, hydration of the surfactant head group, intermicellar interactions, and the intermicellar exchange rate [198,225-228],... 

Iridium and rhodium nanoparticles have also been studied in the hydrogenation of various aromatic compoimds. In all cases, total conversions were not observed in BMI PF6. TOFs based on mol of cyclohexane formed were 44 h for toluene hydrogenation with Ir (0) and 24 h and 5 h for p-xylene reduction with lr(0) or Rh(0) nanoparticles, respectively. The cis-1,4-dimethylcyclohexane is the major product and the cisitrans ratio depends on the nature of the metal 5 1 for lr(0) and 2 1 for Rh(0). TEM experiments show a mean diameter of 2.3 nm and 2.1 nm for rhodium and iridium particles, respectively. The same nanoparticle size distribution is observed after catalysis (Fig. 4). 

A specific example where heterogeneous supports provide nanoparticle size-control is the immobilization of homogeneous silver nanoparticles on polystyrene [366]. This work was extended later to the development of a one-pot method for the size-selective precipitation of silver nanoparticles on PVP-protected thiol-functionalized silica. During the immobilization of very small silver nanoclusters both the size of the silver nanoclusters and the thickness of the silver layer on the support could be controlled directly by the reaction parameters applied (Fi re 16) [367]. 

I(U) characteristics were measured for different temperatures and a Coulomb gap could be observed at 4.2 K, depending on nanoparticle size The smaller particles have smaller capacitances and higher charging energies, and... 

Many different topics are involved in the study of metallic nanoparticles and many fundamental issues can be present for example, which is the infiuence of the nanoparticle size, shape and composition on the chemical activity of heterogeneous catalysts Or, considering another problem, at what size does a small particle behave like the bulk material, for example, changing from an insulator to a semiconductor [9-12] An enormous amount of literature is published on metallic nanoclusters this review is focusing on the relevant problem concerning the characterization of metallic nanosized materials from the morphological and... 

Metal Nanoclusters in Catalysis Effects of Nanoparticle Size, Shape, and Structure... 

Figure 8. TEM and optical absorption of the sample implanted with 5 x 10 Au /cm (a) TEM cross-sectional micrograph (dashed lines represent the free surface and film-substrate interface) (b) nanoparticles size distribution (c) simulated optical spectra (1) Au cluster in a non-absorbing medium with n = 1.6 (2) Au cluster in polyimide (absorbing) (3) Au(core)-C(shell) cluster in a nonabsorbing medium with n = 1.6 (4) the experimental spectrum of Au-implanted polyimide sample, (d) X-ray diffraction patterns as a function of the implantation fiuence.

Changes in the substrate result in changes in particle size distributions, but almost always results in a narrow distribution of nanoparticle sizes. 

Gold Colloidal Nanoparticles Sized to be Suitable Precursors for Heterogeneous Catalysts... 

Zhang L, Lee K, Zhang JJ. 2007. The effect of heat treatment on nanoparticle size and ORR activity for carbon-supported Pd-Co alloy electrocatalysts. Electrochim Acta 52 3088-3094. 

Bergamaski K, Pinheiro ALN, Teixeira-Neto E, Nart EC. 2006. Nanoparticle size effects on methanol electrochemical oxidation on carbon supported platinum catalysts. J Phys Chem B 110 19271-19279. 

Interpretation of pubhshed data is often comphcated by the fact that rather complex catalytic materials are utilized, namely, poly disperse nonuniform metal particles, highly porous supports, etc., where various secondary effects may influence or even submerge PSEs. These include mass transport and discrete particle distribution effects in porous layers, as confirmed by Gloaguen, Antoine, and co-workers [Gloaguen et al., 1994, 1998 Antoine et al., 1998], and diffusion-readsorption effects, as shown by Jusys and co-workers for the MOR and by Chen and Kucemak for the ORR [Jusys et al., 2003 Chen and Kucemak, 2004a, b]. Novel approaches to the design of ordered nanoparticle arrays where nanoparticle size and interparticle distances can be varied independently are expected to shed hght on PSEs in complex multistep multielectron processes such as the MOR and the ORR. 

Examples of STS that are related to catalysis include the work of Goodman and co-workers,18 19 who have studied the electronic structure of palladium and gold nanoparticles on Ti02 as a function of nanoparticle size using I V curves... 

Reed Justin A, Andrew C, Halaas HJ, Paul P, Alex R, Thomas MJ, Grieser F (2003) The effects of microgravity on nanoparticle size distributions generated by the ultrasonic reduction of an aqueous gold-chloride solution. Ultrason Sonochem 10(4—5) 285-289... 

Figure 2.11 TEM images and nanoparticle size distributions of nanopartides synthesized from a modified Brust arrested precipitation technique (a) under ambient conditions and (b) at an applied C02 pressure of 33.0 bar.

Anand, M., You, S.S., Hurst, KM., Saunders, S.R., Kitchens, C.L., Ashurst, W.R. and Roberts, C.B. (2008) Thermodynamic analysis of nanoparticle size selective fractionation using gas-expanded liquids. Industrial and Engineering Chemistry Research, 47 (3), 553-559. 

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