Oxygen molecule ionic forms

Figure 5.5.8-2 The proposed chromophores of animal vision, the Rhodonines, based on Vitamin Al. Retinol (Vitamin A1) is shown for reference. Each chromophore is shown in its ionic form. The oxygen atoms are shown in red. The conjugation critical to absorption in the visual region of the spectrum is shown by the dashed bond. The horizontal line below each molecule shows the relative length of its resonant structure.

At the cathode oxygen molecules react with water molecules to form hydroxide ions. Write an ionic equation for this reaction. 

Figure 5.1 Bond length, vibration frequency and bond energy of the oxygen molecule (3E ) and its various ionic forms (oxygenyl, Oj, superoxide, O2, peroxide, and O3") as a function of bond order.

Bouwman et al. demonstrated that Pt can be used in the ionic form (Pt" and Pt") by dispersing it in a matrix of hydrous iron phosphate (FePO) via a sol-gel process (Pt-FePO)." The hydrous FePO possesses micropores of approximately 2 nm. It has 3 H2O molecules per Fe atom and is thought to also serve as a proton transport medium. The Pt-FePO catalyst exhibited a higher ORR activity than Pt/C catalysts. This catalyst was also found to be less sensitive to CO poisoning because CO did not adsorb onto the catalyst surface. The ORR catalytic activity was attributed to the adsorption and storage of oxygen on the FePO, presumably as Fe-hydroperoxides. However, these catalysts have poor electrical conductivity. There is no published data on the long-term stability of these catalysts in fuel cell environments. 

The oxygen required to form the oxide structure is from the water, either residual or generated during anodization, in the electrolyte. The water molecules enter into the first layers of the oxide and dissociate into ionic species, such as and/or OH", which then migrate toward the silicon/oxide interface under the effect of the electrical field in the oxide. 

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