High-performance graphene oxide/vapor-grown carbon fiber composite polymer actuator

Abstract

The electrochemical and electromechanical properties of poly(vinylidene fluoride-co-hexafluoropropylene)-based actuators using graphene oxide (GO) or graphene (G)/vapor grown carbon fiber (VGCF)/ionic liquid (IL) composite gel electrodes formed are compared with those of actuators using only GO, only G, and only SWCNT. We compare the results with previous results on actuators with electrodes based on single-wall carbon nano-tubes (SWCNTs). In the frequency range 0.005–10 Hz, the GO/VGCF/IL and G/VGCF/IL actuators exhibit higher strains than actuators fabricated without VGCF. For the GO/VGCF/IL actuators, the maximum strain is greater than for actuators made with only GO or only VGCF. The maximum strain for the GO/VGCF/EMI[BF4] actuators is 56% greater than that for an SWCNT-based actuator (GO:VGCF ratio of 7:1)—sufficient for possible practical applications. The maximum generated stress obtained for the GO/VGCF/EMI[TFSI] actuators is 10% greater than that for an SWCNT-based actuator. The maximum generated stresses for GO/VGCF/IL and G/VGCF/IL actuators are greater than those for actuators made with only GO or only G. For a limited number of GO:VGCF and G:VGCF ratios, an electrochemical kinetic model, similar to that used for SWCNT-based actuators, successfully predicts the frequency dependence of the displacement response for GO/VGCF and G/VGCF actuators. These results suggest that flexible, robust films enabled by the synergistic effect obtained by combining graphene and VGCFs can have significant potential as actuator materials for wearable and energy-conversion devices.