Fabrication of graphene/prussian blue composite nanosheets and their electrocatalytic reduction of H2O2

In this work, graphene/prussian blue (PB) composite nanosheets with good dispersibility in aqueous solutions have been synthesized by mixing ferric-(III) chloride and potassium ferricyanide in the presence of graphene under ambient conditions. Transmission electron microscopy (TEM) shows that the average size of the as-synthesized PB nanoparticles on the surface of graphene nanosheets is about 20 nm. Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) patterns have been used to characterize the chemical composition of the obtained graphene/PB composite nanosheets. The graphene/PB composite nanosheets exhibit good electrocatalytic behavior to detection of H₂O₂ at an applied potential of −0.05 V. The sensor shows a good linear dependence on H₂O₂ concentration in the range of 0.02-0.2 mM with a sensitivity of 196.6 μA mM⁻¹ cm⁻². The detection limit is 1.9 μM at the signal-to-noise ratio of 3. Furthermore, the graphene/PB modified electrode exhibits freedom of interference from other co-existing electroactive species. This work provides a new kind of composite modified electrode for amperometric biosensors.