Impurity, interfacial potential

Figure 8. Influence of an electroactive impurity on the interfacial potential-dye concentration relationship. The x axis is the logarithm of the dye concentration, the y axis is the logarithm of the ratio of water volume to nitrobenzene volume, and the z axis is the difference between interfacial potential with and without the impurity. Standard potentials of transport for the impurity cation A (p — — 100 mV and for the anion A (p — +100 mV c = 1 X 10 5 mol/L.

Penetration of the acid through the recast film all the way to the platinum surface was supported by voltammetric evidence and was apparently assisted by the potential multicycling routine employed to maintain an impurity-free platinum surface [1]. Such a study of a filmed platinum electrode immersed in aqueous acid solution is, therefore, less than perfect for providing good data on the rate of ORR at the interface between platinum and hydrated ionomer in a fuel cell cathode, where the only interfacial liquid is distilled water. 

The term "surface-chemically pure", defined by Lunkenheimer Miller (1979), is based on the finding that small amounts of highly surface active contaminations can control the properties of an adsorption layer. The study of the ability of surfactants to change interfacial properties requires an adsorbed layer consisting mainly of the surfactant molecules under study. Therefore, any information about the percentage of a potential impurity, given for commercially available samples, is useless. The reason can be understood easily from the situations shown in Fig. 5.1. 

Disregarding of cause of this effect, the sonication of CNTs in the presence of polymers that are structurally close to the matrix polymer was reported as a desirable approach to ensures compatibility of the flinctionaliznotubes with the polymer matrix to avoid any potential microscopic phase separation in the nanocomposits6,37,38], Interfacial adhesion of polymer matrix to nanotube without any moieties used for functionalizing and/or solublizing also reduce the impurity of final nanocomposite and improve the charge and load transfer efiicency. 

Suitable atomic potentials for Au and for describing the Au-Ni interaction are available [64] and we performed MD simulations over the range of Au impurity concentrations used in the measurements (up to 15 % relative mass [71]). The results of this analysis are shown in Fig. 20, where we see that the Au atoms have the effect of reducing the average length of the strings in the surface interfacial... 

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