Preparation and Supercapacitor Performance of Freestanding Polypyrrole/Polyaniline Coaxial Nanoarrays

Abstract The flexible, freestanding polypyrrole/polyaniline (PPy/PANI) coaxial nanoarray was prepared by removing a titania (TiO 2 ) sacrificial template from PPy/TiO 2 /PANI, which was initially formed by selectively coating PPy and PANI on the outer and inner surfaces of individual TiO 2 nanotubes. PPy/PANI formed a hybrid coaxial structure of PANI nanorods encased in PPy nanopores. The PPy/PANI coaxial nanoarray exhibited a specific capacitance of 209.5 F g −1 at 0.5 A g −1 , presenting higher performance than the PPy nanopore array (114.2 F g −1 ). Its capacitance decreased from 157.5 to 125.2 F g −1 after 500 cycles at 2.0 A g −1 , presenting a reasonable capacitance retention of 79.5 %. The flexible supercapacitor based on the PPy/PANI coaxial nanoarray demonstrated a specific capacitance of 66 F g −1 at 0.5 A g −1 . The PPy/PANI coaxial nanoarray exhibited high pseudocapacitance, moderate cyclibility, and good flexibility, suggesting its promising application in flexible energy storage devices.