Insight into effect of electrolyte temperature on electroactivity degradation of conducting polypyrrole in NaOH

Abstract

The irreversible electroactivity degradation is a key and broad issue for conducting polypyrrole (PPy). PPy degradation involves chemical and electrochemical processes affected by various factors, including doping anions, electrolyte pH, dissolved oxygen (DO), temperature (T), electrode potential, etc. This study probes into the effect of T on electroactivity degradation of PPy in 0.5 M NaOH. Increasing the T (25~80 oC), the degradation kinetics of PPy remains the same first-order relationship, while the degradation rate constant is significantly affected, which shows a maximum value in 50 oC deaerated or 70 oC aerated NaOH, respectively. In deaerated NaOH, the open circuit potential of PPy becomes very negative to reach a reduction state with increasing T, which may restrain penetration of OH- ions into PPy film to inhibit the degradation in its interior. In aerated NaOH, the concentration of DO lowers with increasing T to suppresses the electrochemical process in PPy degradation and decrease its degradation. DO still plays a crucial role in the PPy degradation process at high T. A thorough understanding of the effect of electrolyte T on electroactivity degradation of PPy would offer valuable concepts for in-depth and comprehensive insights into the mechanisms and kinetics of PPy degradation.