▎ 摘　　要

An ascorbic acid (AA) amperometric sensor was fabricated based on a glassy carbon electrode (GCE) modified with a reduced graphene oxide-wrapped hierarchical TiO2 (RGO-TiO2) nanocomposite. The RGO-TiO2 nanocomposite was synthesized via the facial wet chemical method and characterized by scanning electron microscopy and X-ray diffraction. Cyclic voltammetry and amperometric techniques were employed to investigate its electrocatalytic performance towards the AA oxidation. The combined advantages of RGO and TiO2 provide the electrode with higher current response and lower oxidation potential compared with those of bare GCE and TiO2 modified GCE. The proposed electrode can be used for the determination of AA in the wide concentration range from 1 to 1500 mu M with the detection limit of 0.5 mu M. The proposed electrode was successfully used to determine AA in vitamin C tablets and spiked fruit juice. (C) 2014 Institute of Chemistry, Slovak Academy of Sciences