Formation of MnO2-based electrodes with high catalytic activity on the surface of ITO for glucose detection

In this paper, we report on the formation of MnO2-based electrodes for the determination of hydrogen peroxide. We apply thin films of manganese dioxide on the surface of indium tin oxide-coated glass (ITO) using electrochemical deposition under different conditions. MnO2 is a selective catalyst for the decomposition of hydrogen peroxide. Of all methods of sediment formation, we settled on anodic electrodeposition in sulphate electrolytes. By changing the conditions of the process, we can form an electrode material MnO2/ITO with maximum catalytic performance. The electrodes were characterized by SEM, electrochemical impedance spectroscopy, and XPS. The MnO2/ITO and GOx/MnO2/ITO (modified with glucose oxidase enzymes (GOx)) electrodes’ sensing properties were studied by chronoamperometry at an applied potential and by cyclic voltammetry. The film of manganese dioxide with the best catalytic characteristics is formed by electrochemical deposition on the surface of the ITO in electrolyte with pH 1 by CV method during 30 cycles at the range of potentials 0.65 V – 2.1 V vs Ag/AgCl/3M KCl and after this drying at 60°C. the MnO2 films form branching networks which provide an extra-large surface area and show high conductivity. As a proof-of-principle, we developed a GOx/MnO2/ITO working electrode for biosensors for the detection of glucose based on the electrocatalytic determination of hydrogen peroxide generated in the process of enzymatic glucose oxidation. The calibration curve of the GOx/MnO2/ITO electrode shows a linear relationship with the concentration of glucose from 0.1 mM to 3 mM with a correlation coefficient of 0.9938. The sensitivity of such an electrode is 117.8 μA/mmol cm2. The developed electrode can be used in glucose biosensors or similar systems based on other oxidases.