Coupled Electrochemical and Gravimetric Approach for Electroactive Materials

COUPLED ELECTROCHEMICAL AND GRAVIMETRIC APPROACH FOR ELECTROACTIVE MATERIALS 

This cube was based ou a previous scheme of squares visual approach. Here, the axes x, y and z, respectively, represent coupled electron/proton transfer, solvent transfer and acetic acid coordination. Four equilibrium constants describe the coordination reactions for the four pairs of species on the left and right faces of the cube. The authors interpreted their data on partial redox switching of poly(vinylferrocene) films imder permselective conditions in aqueous perchlorate bathing electrolytes which produce films that reach 

For PPY, in general when the anion is small and then mobile, the anion transfer will be dominant, and when the anion is very large (immobile), the cation transfer will be dominant on the time scale of most electrochemical measurements. When PPY is exposed to aqueous tosylate solutions, the authors explored the time scale effects on the competing ion transfers closely associated with solvent transfer. By using the scheme of cubes approach, they showed that on short time scales during reduction, cation entry competes effectively with anion ejection as a means of satisfying film electroneutrality. On longer time scales, the thermodynamically favoured anion mechanism prevails.  

To quantify the relative quantity of solvent and ion for a permselective film, the ratio p of the flux of water [/w = (dWw/df)/A] divided by the flux of counterions [/ion = (dwion/df)/A], at any time, potential E or charge level q, is calculated from experimental data, mion is obtained from q using Faraday s law (wion = Mioaq/zF, where Mion is the molar mass of the ion and zF is its charge) and = mtoM - rriioa- 

More recently, Bruckenstein and Hillman have proposed a new model for the population of electroactive film mobile species (ion and solvent) under a range of thermodynamically and kinetically controlled conditions that allows the film state to be visualized in three dimensions, including E(F), q (C cm ), and A-space, where A represents the film composition and contains the concentrations of the individual mobile species populations, /j (molcm ). For a permselective film undergoing a redox process. 

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IV. COUPLED ELECTROCHEMICAL AND GRAVIMETRIC APPROACH FOR ELECTROACTIVE MATERIALS... 

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