Nanodispersion procedure

Table 3.5 compares the maximum power densities of the catalysts supported on very thin and thin H-CNFs following the nanodispersion procedure described above. Nanodispersion seems to be effective in improving the power density for thin H-CNF-supported catalysts, probably due to an increased number of supporting... 

The reprecipitation strategy lies in the conversion of the products dissolved in a suitable organic solvent into nanodispersed systems in a different medium by a precipitation/condensation procedure. On the other hand, the ion-association strategy can produce ion-based dye nanoparticles in pure aqueous media by utilizing a water-insoluble ion-pair formation reaction. The following example shows the size-dependent absorption properties for the cation-based pseudoisocyanine (PIC see the chemical structure in Fig. 4) dye nanoparticles. 

The catalyst impregnation on the dispersed CNFs must be carefully optimized to obtain a sufficient dispersion of noble metals. Dispersion ofthe CNF in the particular solvent is desirable for uniform impregnation ofthe catalyst. CNFs with very small diameter are very important for effective dispersion. Sophisticated procedures for dispersion must be applied. In the present study, nanodispersion at an impeller agitation of 16 500 rpm was applied to disperse the thin CNFs better. 

For the preparing of nanodispersed electrocatalysts which are composed of two, three or even more elements, the procedure of Bonnemann became very popular. This preparation method produces a well-defined molecular mixture and where possible well-defined alloys of the elements in the electrocatalyst particles of nanometer size. It is essentially based on reductive precipitation of metals from their salt solutions in aprotic media by a borohydride, a very strong reductant. The objective is the forced co-deposition of metals irrespective of their redox potential or different degree of nobility. 

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