Evaluation of piezoelectric property of reduced graphene oxide (rGO)-poly(vinylidene fluoride) nanocomposites

We improved the piezoelectric property of poly(vinylidene fluoride) (PVDF) by employing graphene. The reduced graphene oxide (rGO)-PVDF nanocomposites were prepared by a solution casting method and the rGO contents ranged from 0.0 wt% to 0.2 wt%. To induce the piezoelectric beta-phase crystal structure, the nanocomposite films were drawn in a ratio of 4-5 and polarized by a step-wise poling method. To evaluate the piezoelectric property, the output voltages of the rGO-PVDF nanocomposite films were measured through extensive experimental vibration tests. The experimental results show that the rGO-PVDF nanocomposite film with 0.05 wt% rGO loading possesses the highest output voltage compared with other loadings, which is around 293% of that of the pure PVDF film. Moreover, it can be found that with the increase of the rGO content from 0 wt% to 0.2 wt%, the output voltage tends to have a peak at 0.05 wt%. The main reason for this phenomenon is that a more beta-crystalline phase can be formed at those rGO loadings, as confirmed by XRD and FT-IR spectrum analyses.