The Determination of the Charge-Transfer Rate at Ultra-Micro Film-Coated Electrodes by Using Super Fast Pulse Voltammetry

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The purpose of the present work is to establish the determination procedures of the charge-transfer rate at ultra-micro film-coated electrodes by using super fast pulse and sweep voltammetries (SFV) and to characterize the features of the use of these electrodes.The advantageous features of the use of microelectrodes in SFV are the elimination of iR drop effect due to very low cell current and the enhanced ratios of faradaic/non-faradaic response due to much diminished charging currents of electrical double layer. Thus, using SFV at microelectrodes, where scan rates of potential up to ca 10^5Vs^<-1>and step rates of potential up to ca 1 sec are attainable, it has become possible to examine straightforwards and reliably fast electrochemical kinetics, the determination of which was very difficult or impossible with a conventionally sized electrode. We here succeeded in the determination of the heterogeneous electron-transfer rate constants of metal complexes (Mo(CN)^<4-/3->_ , W(CN)^<4-/3->_ , Os(CN)^<4-/3->_ etc.). We have studied the kinetics and thermodynamics of the electrode reactions at polymer-coated electrodes where the above-mentioned multi-valent anionic complexes are confined electrostatically in cationic polymer films on electrode surfaces. A kinetic examination of the charge-transport processes at electroactive electropolymerized films-coated electrodes has also been conducted by SFV, which proved to be useful as described above.In this research, there have been many interesting developments in attempting to unravel the charge-transfer processes on polymer-coated electrodes. These advances have opened up whole new areas of investigation which combine modern aspects of electrochemistry, polymer chemistry, organic chemistry, inorganic chemistry, biochemistry, physics, etc.