3D Graphene–Cobalt Oxide Electrode for High-Performance Supercapacitor and Enzymeless Glucose Detection

Abstract

Using a simple hydrothermal procedure, cobalt oxide (Co₃O₄) nanowires were <i>in situ</i> synthesized on three-dimensional (3D) graphene foam grown by chemical vapor deposition. The structure and morphology of the resulting 3D graphene/Co₃O₄ composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. The 3D graphene/Co₃O₄ composite was used as the monolithic free-standing electrode for supercapacitor application and for enzymeless electrochemical detection of glucose. We demonstrate that it is capable of delivering high specific capacitance of ∼1100 F g^–1 at a current density of 10 A g^–1 with excellent cycling stability, and it can detect glucose with a ultrahigh sensitivity of 3.39 mA mM^–1 cm^–2 and a remarkable lower detection limit of <25 nM (S/N = 8.5).