3D graphene-cobalt oxide electrode for high-performance supercapacitor and enzymeless glucose detection

Using a simple hydrothermal procedure, cobalt oxide (Co ₃O ₄) nanowires were in situ synthesized on three-dimensional (3D) graphene foam grown by chemical vapor deposition. The structure and morphology of the resulting 3D graphene/Co ₃O ₄ composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. The 3D graphene/Co ₃O ₄ 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).