Surface oxygen complexes chemical analysis

Another theory claims that a protective complex between the metal and the CP is formed in the metal-polymer interface. Kinlen et al. [73] found by electron spectroscopy chemical analysis (ESCA) that an iron-PANl complex in the intermediate layer between the steel surface and the polymer coating is formed. By isolating the complex, it was found that the complex has an oxidation potential 250 mV more positive than PANI. According to Kinlen et al. [73], this complex more readily reduces oxygen and produces a more efficient electrocatalyst. 

In the non-contact area, a thin film of adsorbed organic thiophosphate and iron oxy-hydtoxides is clearly identified. The iron oxide-related oxygen clearly dominates outside the contact area, whereas the contact region consists mostly of phosphate-type oxygen. These results illustrate the complexity of the surface chemical analysis of a tribostressed sample. 

FIGURE 6 Schematic representation of an oxide catalyst with its functional compartments in various structural states for high (back) and low (front) chemical potentials of oxygen. The arrows and the question mark indicate the complex distribution of oxygen in its dual role as a reactant at the surface and as a constituent of the catalyst material in the bulk. Its abundance is controlled by the presence of reducing species in the gas phase leading to a dependence of the results of XRD structural analysis on the availability of reducing gas-phase species. For details and references, see the text. 

Zirconium tris-neopentyl surface complex 1 was synthesized by the sublimation of tetra-neopentylzirconium complex onto the surface of partially dehydroxylated silica at 500°C [26, 27] and fully characterized by IR, NMR, EXAFS, elemental analysis, and gas quantification methods as well as chemical methods [3, 28, 29]. Furthermore, in order to confirm its surface structure, the grafting experiment was carried out with deuterated silica and tetra-neopentylzirconium. Evolution of 1 mol of deuterated neopentane per mole of grafted zirconium proved that there is a single bond between zirconium and oxygen. This monopodal surface structure was further confirmed by EXAFS experiment with 1. 

Unfortunately, it is not always that simple for a variety of reasons. First, we had to assume that the bulk liquid was well mixed, and it may not be. If it is not, we shall be averaging our values in some unknown fashion, and we may find that our correlation extrapolates unreliably. Second, we may find that our data do not fit an exponential form like Eq. 8.4-5. This can happen if the oxygen transferred is consumed in some sort of chemical reaction, which is true in aeration. Third, we do not know which independent variables are important. We might suspect that ka varies with tank diameter, or sparger shape, or surface tension, or the phases of the moon. Such variations can be included in our analysis, but they make it complex. 

---