Enhanced electrochemical charge storage performance by doping of copper phthalocyanine-3,4′,4″,4‴-tetrasulfonic acid tetrasodium salt into polypyrrole/multi-walled carbon nanotubes 3D-nanostructured electrodes

With the increasing focus on energy crisis and environmental protection, polypyrrole/muti walls carbon nanotubes (PPy/MWCNTs) composites which possess relatively high specific capacitance are a class of promising electrode active material for energy storage devices. This study proposes a method using two dopants, copper phthalocyanine-3,4′,4″,4‴-tetrasulfonic acid tetrasodium salt (CuPcTs) and phytic acid (PA), for adjusting the porous nanostructure and improving the electrochemical performance of PPy/MWCNTs electrodes. Compared with the particle-like PPy/MWCNTs and PA-PPY/MWCNTs (p-PPy/MWCNTs) electrodes, the 3D fiber-like CuPcTs-PPy/MWCNTs (c-PPy/MWCNTs) electrodes with a smaller diameter and higher specific surface area can provide more electron successive pathways and ion diffusion tunnels and active sites. The c-PPy/MWCNTs electrodes exhibit the highest specific capacitance of 488 F g−1 @ 5 A g−1 and 451 F g−1 @ 10 mV s−1, which is approximately 2 and 1.6 times of p-PPy/MWCNTs and PPy/MWNCTs with the specific capacitance of 265 F g−1 @ 5 A g−1and 246 F g−1@ 5 A g−1 and 288 F g−1 @ 10 mV s−1 and 267 F g−1 @ 10 mV s−1, respectively. The PPy/MWCNTs doping with CuPcTs can be used as an excellent electrode for the fabrication of energy storage devices and affords a modifying method for other active materials.