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 multiwalled 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 × 10−6 M to 1.8 × 10−3 M, a high sensitivity of 1.08 × 106 μA M−1 cm−2 and a detection limit of 8.0 × 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.