Electrochemical behavior of five progressively alkylated thiazine dyes has been investigated at glassy carbon/montmorillonite and glassy carbon/zeolite electrodes. Quantitative characteristics, associated with the positions of peak potentials ( and ) and current ratios ( ), are measured with scan rates. The peak current observed in the modified electrodes is dependent on both the porosity and nature and number of sites involved in partitioning the complex into film. The values of diffusion coefficient for different dyes have been calculated from electrochemical data. It is suggested that in clay-modified electrode along with physical diffusion the process of electron hopping seems to be most likely. 1. Introduction Cyclic voltammetry (CV) is an important electroanalytical method used to analyze the electronically activated molecules and its corresponding chemical reactions. In other words, the CV response may provide necessary information to the kinetics along with the identification of side and final products of different electrochemical reactions [1]. Nanocrystalline thin films of various metal oxides, namely, SnO2, ZnO, and TiO2 with highly porous structure have drawn the interest of different researchers during the last few decades because of their use in different photochemical cells as photosensitive semiconductor electrodes [2–5]. These electrodes are being used in controlled analysis of some ions and some electroactive biological species, because of their use and selectivity [6, 7]. It has been found that dye-modified electrodes exhibit better electrochemical activity in comparison to that of bare electrodes [8]. A large number of electrochemists show their attention to the clay-modified electrodes due to the unique layered structure of the clay and its ion exchange properties. Different techniques, namely, covalent attachment and polymer-film casting on electrodes are generally employed for the modification in electrochemical and polyelectrochemical studies of dye-incorporated clay-modified electrodes. In an early work Kamat [9] observed a quasi-reversible oxidation wave of thionine in a clay-modified electrode which is comparable to the reversible wave of the same species in an unmodified electrode. The conclusion was that the dye continued its electrochemical identity even in the clay film. Other researchers also observed similar electrochemical behavior to modified electrodes coated with dyes [10, 11]. For a diffusion type cyclic voltammogram of a dye in a clay-modified electrode the peak current is linearly dependent on (where is the scan
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