A highly sensitive hydrogen peroxide amperometric sensor based on MnO2-modified vertically aligned multiwalled carbon nanotubes

In this report, a highly sensitive amperometric sensor based on MnO2-modified vertically aligned multi-walled carbon nanotubes (MnO2/VACNTs) for determination of hydrogen peroxide (H2O2) was fabricated by electrodeposition. The morphology of the nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometer and X-ray diffraction. Cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were applied to investigate the electrochemical properties of the MnO2/VACNTs nanocomposite electrode. The mechanism for the electrochemical reaction of H2O2 at the MnO2/VACNTs nanocomposite electrode was also discussed. In borate buffer (pH 7.8, 0.20 M), the MnO2/VACNTs nanocomposite electrode exhibits a linear dependence (R = 0.998) on the concentration of H2O2 from 1.2 x 10(-6) M to 1.8 x 10(-3) M, a high sensitivity of 1.08 x 10(6) mu A M-1 cm(-2) and a detection limit of 8.0 x 10(-7) M(signal/noise = 3). Meanwhile, the MnO2/VACNTs nanocomposite electrode is also highly resistant towards typical inorganic salts and some biomolecules such as acetic acid, citric acid, uric acid and D-(+)-glucose, etc. In addition, the sensor based on the MnO2/VACNTs nanocomposite electrode was applied for the determination of trace of H2O2 in milk with high accuracy, demonstrating its potential for practical application. (C) 2010 Elsevier B.V. All rights reserved.