Selective and sensitive phenothiazine sensor based on hexagonal CuO/Co3O4 decorated on reduced graphene oxide catalyst

Abstract

Binary transition metal oxides with conducting carbon materials are increasingly accepted in electrochemistry. Here, a highly effective binary CuO/Co3O4 metal oxide electrocatalyst with hexagonal morphology was synthesized directly on cobalt and copper containing solid precursors by a facile hydrothermal method. Further, the activity of CuO/Co3O4 was enhanced by combination with conductive reduced graphene oxide (rGO). The physical properties of the resulting material (CuO/Co3O4@rGO) were investigated using various spectroscopic and microscopic techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). CuO/Co3O4@rGO coated on a screen-printed carbon electrode (SPCE) was used as an electrode for the detection of antipsychotic drug phenothiazine (PTZ) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in phosphate buffer solution (PBS, pH 5.0). The CuO/Co3O4@rGO/SPCE showed a wide linear range of 0.01–2.1 μM with a detection limit of 0.64 * 10−9 mol/L and a sensitivity of 1.8 μA/μM cm2 for PTZ detection. In addition, the PTZ sensor has reliable selectivity, stability and accuracy. Finally, the practicality of the fabricated sensor was tested in human serum and urine samples with acceptable recoveries.