Application of ascorbic acid in the synthesis of rGO/micro-octahedral Cu2O nanocomposites and its effect on the wide linear response range of glucose detection

Abstract

In this study, a simple and scalable method with the application of Ascorbic acid has been reported for the fabrication of decorated reduced graphene oxide by Cu2O micro-octahedrons (rGO/ micro-octahedral Cu2O nanocomposites) for non-enzymatic glucose sensor using differential pulse voltammetry (DPV) techniques. The structural study of rGO/ micro-octahedral Cu2O using detailed XRD analyses, Raman spectroscopy, FESEM imaging, EDX elemental mapping and BET-BJH analyses revealed that the application of ascorbic acid in the synthesis process enhances the morphology, surface area, charge transfer and electrocatalyst properties of the nanocomposite. XPS analysis revealed the significant reduction of GO with the distinct peak of C–C in the C 1 s orbital scan. Quenching of satellite peaks (Cu2+) in Cu 2p orbital scan accompanied by the appearance of Cu-C new bond were indications of CuO phase elimination and hybridization of rGO/Cu2O structure. The modified electrodes with Nafion showed a wide linear span of 1 µM- 9 mM for glucose detection, high sensitivity of 415 µA mM−1 cm−2 with low detection limit of 0.96 µM and significantly being selective among different species. The sensitivity measurement without Nafion as a Nafion-free modified electrode was still high as 24.8 µA mM−1 cm−2 with the same wide linearity range and low detection limit of 0.53 µM. The stability of 97.95% in signal change after 56 days and repeatability of the modified electrode with relative standard deviation of 4.06% were also obtained. The modified GC/rGO/micro-octahedral Cu2O electrode revealed its electrocatalytic activity toward glucose oxidation that was excellently competitive with HPLC measurement of glucose in human serum.