Performance enhancement of ZnO nanorod-based enzymatic glucose sensor via reduced graphene oxide deposition and UV irradiation

This paper reports the performance enhancement of a ZnO nanorod-based enzymatic glucose sensor with reduced graphene oxide (rGO) introduced between the ZnO nanorods and indium tin oxide (ITO) electrode and then stimulated under UV irradiation. The electrochemical characterization indicates that the rGO not only facilitates electron transfer through the ZnO nanorods to the ITO electrode but also inhibits the fast recombination of the photo-generated electrons and holes. The UV irradiation stimulates holes in the valence band of the ZnO nanorods, which as oxidants enhance the catalytic activity of the glucose oxidase (GOx) towards glucose. The rGO increases the sensitivity of the ZnO nanorod-based glucose sensor by 1.6 times and decreases the detection limit by 2.3 times. Together with the rGO, the UV irradiation further increases the sensitivity by 1.7 times and diminishes the detection limit by 2 times. Moreover, the as-prepared glucose sensors exhibit excellent selectivity to urea, uric acid, and ascorbic acid, and can reliably determine the glucose concentration in a serum sample. The results have the potential to improve the performance of other enzymatic biosensors.