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

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