A sensitive non-enzymatic electrochemical glucose sensor based on a ZnO/Co3O4/reduced graphene oxide nanocomposite

Abstract

A novel sensitive and selective ZnO/Co₃O₄/rGO nanocomposite was fabricated using a hydrothermal method and used as a non-enzymatic electrochemical sensor for the detection of glucose. The morphology and structure of the ZnO/Co₃O₄/rGO composite were characterized using UV-vis spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) techniques. The electrochemical properties of the as-synthesized nanomaterials were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and single potential time base (TB) amperometry. The ZnO/Co₃O₄/rGO nanocomposite exhibited excellent electrochemical performance with higher catalytic activity, lower working potential (0.55 V), and low charge transfer resistance for the electrochemical oxidation of glucose, which can be attributed to the presence of high conductive reduced graphene oxide sheets on the surface of the electrode. Under optimal conditions, the ZnO/Co₃O₄/rGO glassy carbon electrode (GCE) modified electrochemical glucose sensor demonstrated a wide linear range (0.015–10 mM), high sensitivity (1551.38 μA mM⁻¹ cm⁻²), low detection limit (0.043 μM) and fast response time (∼3 s) to glucose determination. In addition, the ZnO/Co₃O₄/rGO/GCE sensor was able to detect glucose even in the presence of biologically interfering molecules and chloride ions. The sensor achieved appreciable repeatability, reproducibility, and long-term stability. Moreover, the practical application of the ZnO/Co₃O₄/rGO/GCE electrochemical sensor is very appropriate for the detection of glucose in real samples for medical diagnostic and food industries, and the results positively agreed with those collected using the spectrophotometric method in the hospital and the glucose label value in food industries.