A sensitive non-enzymatic electrochemical sensor based on acicular manganese dioxide modified graphene nanosheets...

In this work, a novel manganese dioxide-graphene nanosheets (MnO₂-GNSs) composite was synthesized by a facile one-step hydrothermal method, in which manganese dioxide (MnO₂) was fabricated by hydrothermal reduction of KMnO₄ with GNSs. The structure and morphology of MnO₂-GNSs composite were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) analysis and X-ray photoelectron spectroscopy (XPS). A sensitive non-enzymatic electrochemical sensor based on MnO₂-GNSs composite for the detection of low concentration hydrogen peroxide (H₂O₂) was fabricated. The electrochemical properties of MnO₂-GNSs composite modified glassy carbon electrode (MnO₂-GNSs/GCE) were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometry. The observations confirmed that the fabricated sensor exhibited high electrocatalytic activity for oxidation of H₂O₂ owing to the catalytic ability of MnO₂ particles and the conductivity of GNSs. Under the optimum conditions, the calibration curve was linear for the amperometric response versus H₂O₂ concentration over the range 0.5-350 μM with a low detection limit of 0.19 μM (S/N = 3) and high sensitivity of 422.10 μA mM^-1 cm^-2. The determination and quantitative analysis of H₂O₂ in antiseptic solution on MnO₂-GNSs/GCE exhibited percent recovery of 96.50%-101.22% with relative standard deviation (RSD) of 1.48%-4.47%. The developed MnO₂-GNSs/GCE might be a promising platform for the practical detection of H₂O₂ due to its prominent properties including excellent reproducibility, good anti-interference and repeatability.