Design of polypyrrole/polyaniline double-walled nanotube arrays for electrochemical energy storage.

The novel hybrid polypyrrole (PPy)/polyaniline (PANI) double-walled nanotube arrays (DNTAs) were designed to exploit the synergistic effects and shape effects for supercapacitive energy storage. The PPy/PANI DNTAs showed large specific capacitance (Csp) of 693 F/g at a scan rate of 5 mV/s. The PPy/PANI DNTAs also exhibited good rate capability and high long-term cycle stability (less 8% loss of the maximum specific capacitance after 1000 cycles). The synergistic effects between PPy and PANI, the shape effects of nanotube arrays and double-walled nanostructures, and high utilization rate of electrode are crucial for the outstanding performance of PPy/PANI DNTAs. The large Csp, good rate capability, and high long-term cycle stability offered by the PPy/PANI DNTAs, make them promising candidate electrodes for high-performance supercapacitors.