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

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 o C), 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 o C deaerated or 70 o C 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.