Start
Apr 04, 2013 - 17:00
End
Apr 04, 2013 - 18:00
Venue
Room 118 (Creativity Hall) Ground Floor Chemical Engineering Department
Event Type
Speaker
Asfiya Q. Contractor PhD Student IIT Bombay
Title
Electrochemical Characterization of Conducting Polymer Films
Abstract: Understanding the charging behaviour of a conducting polymer is important from the point of view of its use as a charge storage device. Potentiodynamic techniques such as step- pulse- or cyclic-voltammetry and impedance spectroscopy are some common techniques employed for the study of charging dynamics of conducting polymer films. Since the charging process involves several coupled dynamical steps the overall dynamics becomes so complex that decoupling of the overall processes into individual steps is very difficult and can often be ambiguous. One way to overcome this difficulty is to perform a suitable redox reaction on the conducting polymer film under steady state condition. By monitoring steady state current as a function of the electrode potential for a fixed composition of the electrolyte it is possible to obtain an insight into the nature of the charge storage characteristics of the film as shown in this work. It is possible to study the energy state of the stored charge by studying the shifts in the reaction equilibria in different ranges of electrode potential. Using this technique it is possible to elucidate the energy band structure of the charge storage in the polymer. As a test case polyaniline film was chosen as the substrate. To keep the analysis simple we needed to choose an elementary one-step redox reaction. For the present study we chose a redox system involving ferrous-ferric ions. Some experiments were also performed on the redox reaction of quinhydrone. We observed five distinct energy bands in which charge is stored in polyaniline. The transition potentials as well as band energies were quantified using this method. These transition potentials coincided with those observed by other authors using Electron Spin Resonance Spectroscopy and Raman Spectroscopy. Both the systems studied yielded identical energy bands indicating that our method does not depend on the system chosen and is universal.