Electrochemical synthesis of carboxaldehyde functionalized polyindole for highly efficient electrochemical energy storage

Conducting polymers as supercapacitors materials have attracted a lot of attention due to their high charge density, low cost, high flexibility, and good processability. In this work, the electrodeposition of carboxaldehyde substituted indole and the capacitance performance of the prepared conducting polymers are investigated for the first time. The structure and properties of the prepared polymers are characterized by FT-IR, SEM, TGA, XRD, XPS, TEM, BET and electrochemical techniques. The results of the electrochemical test show that the prepared poly (indole-5-carboxaldehyde) (5-PIC), poly (indole-6-carboxaldehyde) (6-PIC) and poly (indole-7-carboxaldehyde) (7-PIC) possess better thermal stability, morphology and capacitance performance than polyindole (PIn). In particular, 7-PIC exhibits a high specific capacitance of 489 F g−1 at 2.5 A g−1 and retains 87 % capacitance after 5000 cycles test. In this work, the effects of carboxaldehyde substitution on the properties of PIn are systematically studied, and a kind of high-performance electrode material for supercapacitor is demonstrated.