A 3D reduced graphene oxide and flower-like ZnO crystal composite for electrochemical detection of reducing small biomolecules

Three-dimensional reduced graphene oxide (3DrGO) and a flower-like zinc oxide (ZnO) crystal were prepared using a hydrothermal method. A stable dispersion of the 3DrGO-ZnO composite was formed by sonication mixing, and was further applied to modify a glassy carbon electrode for direct trace detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The structure, composition and morphology of the as-prepared 3DrGO-ZnO composite were characterized using X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy, respectively. Compared with bare, 3DrGO and ZnO electrodes, the 3DrGO-ZnO electrode exhibited an obvious electrocatalytic enhancement effect. Furthermore, the 3DrGO-ZnO electrode could well distinguish and enhance the differential pulse voltammetry signals of AA, DA and UA. Under the selected conditions, the peak current responses to AA, DA and UA were linear in the range of 100-2500 mu mol L-1, 2.00-35.0 mu mol L-1, and 1.00-150 mu mol L-1, respectively. To verify its possible application, the constructed modified electrode was successfully used for the analysis of real samples with satisfactory results.