Polypyrrole-hemin-reduce graphene oxide: rapid synthesis and enhanced electrocatalytic activity towards the reduction of hydrogen peroxide

An efficient and eco-friendly microwave-assistant method is developed to synthesize a ternary composite of polypyrrole-hemin-reduced graphene oxide (PPY-He-RGO). The polymerization of the pyrrole monomer and the reduction of graphene oxide are performed simply by microwave heating without using a strong reducing or oxidizing agent in an isopropanol/H2O mixed medium. Hemin molecules are immobilized on reduced graphene oxide (RGO) sheets and can still retain high electrocatalytic activity toward the reduction of H2O2 in the final composite. The conducting RGO and polypyrrole with a well-controlled nanostructure provide a highly conductive network to the ternary composite, which can promote the electron transfer between hemin, analytes and electrodes, leading to an improved electrocatalytic activity. The PPY-He-RGO can act as a third-generation mediator and mimic enzyme for the fabrication of a hydrogen peroxide biosensor. The as-prepared PPY-He-RGO electrode exhibits a high sensitivity to H2O2 with a low detection limit of 0.13 μm. The efficient microwave heating provides an opportunity for large-scale production of PPY-He-RGO ternary nanocomposites as a kind of mimic enzyme for biosensors.