Reduced Graphene Oxide-Supported Co₃O₄ Nanocomposite Bifunctional Electrocatalysts\nfor Glucose–Oxygen Fuel Cells

Abstract

Designing\na high-performance\nelectrocatalyst\nis very important for producing energy systems such as glucose–oxygen\nfuel cells (GFCs). Here, we report the preparation of a nanocomposite\nmaterial consisting of different weight percentages of reduced graphene\noxide-supported (5, 10, and 20 wt %) cobalt oxide nanoparticles (rGO–Co₃O₄). The corresponding modified electrodes exhibited\nbifunctional electrocatalytic behavior toward both glucose oxidation\nand oxygen reduction reaction (ORR). The rGO–Co₃O₄ nanocomposite material is prepared and characterized\nby thermogravimetry analysis, X-ray diffraction, diffuse reflectance\nspectroscopy, Fourier transform infrared spectroscopy, selected area\nelectron diffraction, the Brunauer–Emmett–Teller method,\nthe Barret–Joyner–Halenda method, energy-dispersive\nX-ray spectroscopy, high-resolution transmission electron microscopy,\nand electrochemical analysis. Among different weight percentages of\nrGO, 10 wt % GO in the rGO–Co₃O₄ nanocomposite-modified\nelectrode shows stable electrooxidation of glucose with a rapid response\ntime of 1 s with a 0.4 μM limit of detection and a 1008 μA\nmM^–1 cm^–2 sensitivity. In addition,\nrGO–Co₃O₄ (10 wt % GO)-modified electrodes\nshow less negative potential with a large kinetic current and better\ncatalytic durability for ORR. Thus, rGO–Co₃O₄ (10 wt % GO) is employed as a bifunctional catalyst in cost-effective\nGFCs and obtains a power density output of 0.7319 mW cm^–2.