Potentiometric Sensing of Nitrate Based on Conducting Imprinted Poly (Pyrrole-<i> <scp>c</scp>o</i>-Pyrrole-3-Carboxylic Acid), Plausible Self-Doped Effect

In typical solid-contact potentiometric sensing, ion selective membranes (ISMs) play the role of recognizing the target analytes. A variety of solid-contact materials have been utilized to realize the ion-to-electron transduction. However, the ISMs show some drawbacks during practical application. Recent research efforts have been devoted to developing ISM-free potentiometric sensing. In this work, an ion-imprinted conducting poly (pyrrole- co -pyrrole-3-carboxylic acid) copolymer was investigated to achieve the ISM-free potentiometric sensing toward nitrate, an important anion to monitor in the environment. The copolymer-based electrochemical sensor afforded good potentiometric responses toward nitrate in a Nernstian manner, exhibiting superior or comparable sensing performances with existing ISM-based potentiometric sensors. Compared with polypyrrole homopolymer, the introduced carboxylate group in the side chain of the copolymer was likely to contribute to the redox activity, enabling better ion-to-electron transduction. More importantly, a unique self-doped effect was observed in the prepared poly (pyrrole- co -pyrrole-3-carboxylic acid), extending the working pH range of polypyrrole family and providing potential implications to develop electrochemical sensors when the environmental pH matters.