Controllable Synthesis, Core-Shell Nanostructures, and Supercapacitor Performance of Highly Uniform Polypyrrole/Polyaniline Nanospheres

The sea urchin-like polyaniline (i.e., PANI) had been successfully grown on the surface of polypyrrole (i.e., PPy) nanospheres to form PPy@PANI composites with a core-shell structure by dilute solution polymerization. The shell thickness of the PANI could be adjusted from 20 to 120 nm via modulating the moles of aniline. The core-shell structure and molecular structure of PPy@PANI composites had been confirmed by TEM images and Raman and XPS spectra. Interestingly, the core-shell PPy@PANI nanospheres exhibited outstanding electrochemical properties and could be acted as a good electrode material for supercapacitors. The maximum specific capacitance (i.e., SC) of the PPy@PANI electrode was 510 F/g at 10 mV/s. The good rate capability (about 27.6% loss of the initial SC from 10 to 200 mV/s) and long cycle stability (the SC loss was about 12.4% after 1000 charge/discharge cycles) had been also verified by the further electrochemical measurement. It was ascribed to the synergistic effect between cored PPy and shelled PANI layer. In addition, the SC value of core-shell PPy@PANI nanospheres was closely related to the thickness of the PANI shell and the shape effect of sea urchin-like PANI. Moreover, the high utilization rates of PPy and PANI were crucial for the excellent supercapacitive energy storage of core-shell PPy@PANI nanospheres.