Preparation and electrochemical performances of PEDOT/sulfonic acid-functionalized graphene composite hydrogel

•PEDOT/graphene composite hydrogel was prepared by in situ polymerization.•The 3D porous structure of hydrogel is controlled by supramolecular self-assembly.•Introduction of graphene caused the improved conductivity and specific capacitance.•A high capacitance value of 220 F/g was obtained at a high current density of 5 A/g.

Poly(3,4-ethylenedioxythiophene) (PEDOT)/sulfonic acid-functionalized graphene composite hydrogel was prepared by introducing microcontent of sulfonic acid-functionalized graphene (SFG) using in situ polymerization. The specific capacitance of the composite hydrogel was significantly improved by the introduction of SFG when the feeding ratio of SFG to 3,4-ethylenedioxythiophene (EDOT) was as low as 1:1000, the specific capacitance of the composite hydrogel can reach 93 F/g, which was more than two times than that of the pure PEDOT hydrogel (39 F/g). The composite hydrogel showed a high specific capacitance of 135 and 220 F/g at high current density (5 A/g) when KI and K3Fe(CN)6–H2SO4 solution were employed as redox-active electrolytes, respectively. The composite hydrogel in K3Fe(CN)6–H2SO4 can be used as potential electrode material for supercapacitor applications.