Recovery of Electrochemical Properties of Polyaniline-Based Multilayer Films with Improved Electrochemical Stability

Owing to its unique structure and reduction–oxidation (redox) properties, polyaniline (PANI) has been widely used in diverse applications, including sensors, solar cells, electrochromic devices, batteries, and supercapacitors. However, irreversible redox reactions between different oxidation states of PANI often result in low chemical and electrochemical stability, deteriorating devices’ performance characteristics. Herein, we fabricated PANI-based multilayer films using spin-assisted layer-by-layer assembly, providing significantly improved chemical and electrochemical stability compared to the PANI homopolymer. More importantly, we found that the electroactivity and electrical conductivity of PANI-based films can be restored by a simple chemical reactivation process using an acidic aqueous solution. The re-doping process successfully recovers the electrochemical properties of PANI, even improving the electroactivity and conductivity characteristics of polyacid-doped PANI films, attributed to the secondary doping and rearrangement of polymers. Furthermore, we demonstrate that the performance of PANI multilayer films for ammonia sensors is successfully restored after the reactivation process.