Spectrocyclic voltammetry

Nafion film coated on an ITO electrode to understand the structural transformations of the dimer in the Nafion coating during the catalytic water oxidation process . The absorption spectral changes observed during the oxidation scan from 0.4 to 1.4 V (s. SCE) (Fig. lOA) showed a decrease in the absorbance at 655 nm with simultaneous increase in the absorbance at around 450 nm with clear isosbestic points at 430 and 545 nm. In the reductive scan from 1.4 to 0.4 V (vs. SCE) (Fig. lOB), the absorbance at 655 nm increased and a simultaneous decrease in the absorbance at 450 nm was observed with an isosbestic point at 555 nm. The absorbance at 655 nm was almost recovered back. Initially the oxidation of the dimer complex H20-Ru" -Ru "-0H2 leads to the formation of H20-Ru "-Ru -0H2 with an absorption maximum at around 450 nm and further oxidation at higher positive potentials must lead to Ru -Ru formation in a successive oxidation process. The Ru -Ru would be rapidly reduced by water molecules to produce H20-Ru -Ru -0H2 at pH 1. The same in situ spectrocyclic voltammetry experiments at pH 9.3 showed an absorption maximum at around 500 nm with the formation of H20-Ru" -Ru -OH in the Nafion film. In relevant to the absorbances at 450... 

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