Electrochemical synthesis of graphene/polypyrrole nanotube composites for multifunctional applications

A conducting composite film has been fabricated using graphene oxide (GO) and pre-prepared one-dimensional polypyrrole (PPy) nanotube as the feedstock. GO with various oxygen-containing groups effectively promotes the dispersion of well-defined PPy nanotubes to obtain a stable and homogeneous GO/PPy complex solution. By a one-step and large-scale electrochemical reduction, the graphene/PPy nanotube composite film is successfully synthesized. Graphene nanosheets uniformly cover the surface of the electrode and PPy nanotubes act as spacers and conducting bridges to prevent the restacking of graphene sheets and connect the isolated graphene nanosheets. Electrochemical experiments indicate that the composite films have high performances due to the combination of the advantages of graphene and PPy nanotube. When the graphene/PPy nanotube composite is directly used as the supercapacitor electrode, it shows high specific capacitance and good cycling stability during 1000 charge/discharge cycles. Furthermore, an electrochemical biosensor is constructed through the entrapment of horseradish peroxidase (HRP) onto the composite film-modified glassy carbon electrode (GCE). The immobilized HRP showed high catalytic activity for the reduction of H2O2, which may be ascribed to high conductivity, great surface coverage, and good biocompatibility of the prepared graphene/PPy nanotube composite film. This method may be extended to prepare other conducting composite films with structure controllable nanostructures in large scale for the application of electrochemical fields.