Copper average particle size

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).

Fig. 7. The average particle sizes of copper ( ), its CuO precursor (O), and zinc oxide (A) determined from X-ray diffraction line broadening (41). [Reprinted with permission from J. Phys. Chem. 83, 3118 (1979). Copyright (1979) American Chemical Society.]...

Azides must also be analyzed for trace-metal content, such as copper, mercury, or thallium, because of the possibility of enhanced sensitivity. Other tests include analysis for grit, average particle size, and crystal morphology in confor-... 

Average particle sizes were determined with TEM. For that purpose a drop of the colloidal solution was placed on a carbon covered copper grid (Balzers) and analyzed with a high resolution transmission electron microscope (model JEOL 200 CX). Particle size distributions were determined by optical inspection of the photographs. From this data, metal areas of the catalysts were estimated assuming spherical particle shape and a rhodium surface density of 1.66 10 mol Rh/m [10]. As a reference material for characterization and testing, a commercial rhodium on carbon catalyst (5w% Rh, Aldrich) was used. 

Characterization. Transmission electron micrographs were taken with a JEOL-100 CX n transmission electron microscope in order to obtain the particle size, morphology, and particle size distribution of the sanq>les. The TEM samples were prepared by placing a drop of the colloid on a carbon-coated copper grid and letting the solvent evaporate. The particle sizes were measured with a conq)arator and the average particle sizes and size distributions were determined based on the measurement of at least 100 particles. 

Additives to suppress particle agglomeration may be added to the suspension. This is crucial for low particle sizes [129]. Pfeifer et al. described a technique for wash-coating copper/zinc oxide catalysts onto aluminium microchannels [135], Copper oxide nanoparticles of 41 nm average particle size were mixed with zinc oxide nanoparticles of 77 nm average particle size either by wet mixing with aqueous hydroxy ethyl cellulose or hydroxy propyl cellulose in isopropyl alcohol. Alternatively, the particles were typically milled and then dispersed in aqueous hydroxy ethyl cellulose. The dispersion then filled in the microchannels, resulting in a catalyst layer of 20 pm thickness, which was then calcined in air at 450 °C. The surface area of the samples was around 20 m g . ... 

As can be seen in table 1, with different preparation methods and active metals, the average size of the copper particle for the catalysts A and D were 20.3 nm and 50.0 nm. While those of the catalysts B and C were 51.3 nm and 45.4 run, respectively. CuO, non-supported metal oxide, made by impregnation is sintered and cluster whose particle size was 30 pm. The water-alcohol method provided more dispersed catalysts than the impregnation method. 

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