Phytic acid assisted fabrication of graphene/polyaniline composite hydrogels for high-capacitance supercapacitors

Graphene/polyaniline composites were fabricated by an in-situ chemical oxidative polymerization of aniline in the presence of graphene oxide with the assistance of phytic acid. Here graphene sheets construct large conjugated frameworks for anchoring polyaniline through electrostatic, hydrogen bonding, and pi-pi interactions. Meanwhile, phytic acid functions as the protonation agent for doping polyaniline and also the physical cross-linker for bridging polyaniline chains. Such synergistic effects result in the formation of graphene/polyaniline composite hydrogels. The as-fabricated hydrogels were then used as the additive-free supercapacitor electrodes, which deliver specific capacitances as high as 1217.2 F/g at the scan rate of 10 mV/s, and 865.6 F/g at the current density of 1 A/g in an aqueous electrolyte of 1 M H2SO4, respectively. The initial capacitance remains 78.3% upon increasing to 10 A/g of the current density and retains 82% after charging/discharging 1000 cycles. Such high specific capacitance, good rate capability, and excellent cycling stability are due to the synergistic effect of bifunctional phytic acid and conductive graphene sheets. This work may offer an alternative strategy to produce composite hydrogels for the development of high-performance supercapacitors.