Functional Channel of SWCNTs/Cu2O/ZnO NRs/Graphene Hybrid Electrodes for Highly Sensitive Nonenzymatic Glucose Sensors.

The hybrid electrode of single-wall carbon nanotubes (SWCNTs)/Cu2O/ZnO nanorods (NRs)/graphene used on the current-response nonenzymatic glucose sensor was investigated herein, regarding the mechanism of the formation of functional channel. The synthesis of the hybrid electrode involved four steps. First, the graphene was grown by chemical vapor deposition (CVD) and then wet-transferred onto indium transparent oxide (ITO) glass. Second, a zinc oxide (ZnO) seed layer was sputtered onto the graphene/ITO glass, and ZnO NRs were gradually grown by the hydrothermal method. Third, the ZnO NRs were clad with cuprous oxide (Cu2O) by the electrochemical method. Fourth, the SWCNTs were dropped onto the Cu2O surface, with a Nafion surfactant. X-ray diffraction spectra, scanning electron microscopy spectra, Raman spectra, cyclic voltammograms, and amperometric response diagrams were used to verify the performance of the device. Results showed that sensitivity increased significantly from 11.2 to 289.8 μA mM-1 cm-2, linear range increased significantly from 0.6 to 11.1 mM, and the coefficient of determination (R2) increased from 0.9766 to 0.9923, all by the addition of the SWCNTs/Cu2O functional channel mechanism and without graphene. When the graphene was added to the functional channel electrode, sensitivity increased again from 289.8 to 466.1 μA mM-1 cm-2 at low concentrations.