Electrocatalytic Oxidation of Saccharides at MoO_x/AuNPs Modified Electrode Towards Analytical Application

The MoO_x/AuNPs composite film modified glassy carbon electrode was fabricated by electro-depositing simultaneously gold nanoparticles and molybdenum oxides using cyclic voltammetry. The morphology and topography of the MoO_x/AuNPs composite were characterized by scan electron microscopy and X-ray photoelectron spectroscopy respectively, and the electrocatalytic oxidation of glucose at the MoO_x/AuNPs composite film was investigated and analyzed in detail. It was shown that the MoO_x/AuNPs composite was of strong electrocatalytic activity towards oxidation of glucose as well as other saccharides, so that an attempt was made for direct voltammetric determination of glucose. Then the positive scan polarization reverse catalytic voltammetry was proposed for the first time. Based on this method, the pure oxidation current was extracted by subtraction of the blank current in the reverse scan. The current sensitivity was enhanced tremendously and the signal to noise ratio was improved adequately. The electrocatalytic oxidation of glucose at the MoO_x/AuNPs modified electrode was performed in alkaline medium, a wide linear range from 0.01 mmol/L to 4.0 mmol/L of glucose, a higher current sensitivity of 2.35 mA/(mmol/L·cm²), and a lower limit of detection of 9.01 µmol/L (at signal/noise=3) were achieved. In addition, the electrocatalytic oxidation of other saccharides such as lactose, fructose and sucrose was also evaluated.