Nonenzymatic electrochemical sensing of hydrogen peroxide based on a polyaniline-MnO2 nanofiber-modified glassy carbon electrode

We report the synthesis of polyaniline-manganese dioxide (PANI-MnO2) nanofibers and their applications as nonenzymatic electrochemical sensors for the determination of hydrogen peroxide (H2O2). The PANI-MnO2 nanofibers were synthesized via a one-step mixing process from the as-prepared PANI nanofiber aqueous dispersion and the aqueous solution of KMnO4. The morphology and chemical composition of the synthesized PANI-MnO2 nanofibers were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy, and X-ray diffraction. A facile electrochemical hydrogen peroxide sensor based on a PANI-MnO2-modified glassy carbon electrode (PANI-MnO2/GCE) was fabricated by a drop-casting method, and its electrochemical behavior was investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and amperometry. The results clearly exhibited good electrocatalytic activity of the PANI-MnO2/GCE toward H2O2 reduction in pH 7.4 phosphate buffer solution (PBS). The nonenzymatic H2O2 sensor displayed a wide linear range (5-50 mu M and 0.05-10 mM), low detection limit (0.8 mu M at S/N = 3), high sensitivity (403.3 mu A mM(-1) cm(-2)), and negligible interference from ascorbic acid, uric acid, l-cysteine, and glucose at an applied detection potential of -0.4 V (vs. Ag/AgCl).