A Simple Chemical Procedure for Extending the Conductive State of Polypyrrole to More Negative Potentials

The electronically conductive polymer polypyrrole is an electronic conductor at potentials positive of ca. −0.4 V vs. the saturated calomel electrode (SCE) and an electronic insulator at potentials negative of this value. As a result of this potential‐dependent conductor/insulator transition, a polypyrrole film can be used as an electrode for redox couples with E 0 positive of ca. −0.4 V vs. SCE but cannot be used as an electrode for couples with E 0 negative of this value. We have discovered a simple chemical procedure that extends the conductive state of polypyrrole to ca. −1.1 V vs. SCE. This procedure entails treating the polypyrrole film with aqueous sodium hydroxide. We demonstrate this extension of the conductive state to more negative potentials here. We also propose, and test, a chemical model that explains the extension of the conductive state.