Chemically Bonded Carbon Nanotube Film to a Nanostructured Gold Electrode for Electrochemical Sensing of Hydrogen Peroxide

This paper describes the first application of a covalently attached carbon nanotube film to the nanostructured gold electrode for the electrochemical detection of hydrogen peroxide. The electrodes were made by diazonium salt grafting to the gold surface with the subsequent attachment of carbon nanotubes using a low-temperature synthesis method. The introduction of properly aligned carbon nanotubes significantly increased the electroactive surface area and the current response. Covalent bonding of the nanotubes to gold resulted in a very high stability of the signal under the oxidative conditions. After 540 h of exposure to a high oxidative potential, the current response remained stable, having negligible deviations between the runs. Hydrogen peroxide detection involves an indirect enzyme-free oxidation mechanism, allowing for analysis at low potentials. The use of such a mechanism allows for classifying the system as a fourth-generation H2O2 sensor. Because of the low working potential, a 20-fold excess of fructose, creatinine, dopamine, uric acid, citric acid, and ascorbic acid did not interfere with hydrogen peroxide detection. The presence of functional groups on the carbon nanotube surface provides possibilities for simple functionalization. As an example, the fabricated electrodes were successfully modified with glucose oxidase for glucose quantification.