Hierarchical Co₃O₄ decorated nitrogen-doped graphene oxide nanosheets for energy storage and gas sensing applications

Nano-sized cobalt oxide decorated nitrogen-doped graphene oxide (Co₃O₄@NGO) composite was produced by a feasible and cost-effective hydrothermal route for electrochemical supercapacitors and gas sensor applications. The composite materials formation was ascertained by Raman spectroscopy, X-ray diffraction, and X-ray photo electron spectroscopy analyses. Field emission scanning electron microscopy (FE-SEM) and field emission transmission electron microscopy (FE-TEM) results explored the controlled nanoscale-sized sheet-like morphology for the prepared composite materials. Electrochemical storage properties were studied by cyclic voltammetry (CV), galvanostatic charge–discharge process (GCD), and electrochemical impedance spectroscopy analyses using three-electrode configuration with 3 M KOH electrolyte. The observed results showed ~466 F/g specific capacitance at a current density of 1 A/g for Co₃O₄@NGO composite structure with the capacity retention of 96 % after 5000 cycles. Further, the synthesized Co₃O₄@NGO composite revealed improved detection response, cyclability, and linearity for dimethyl methyl phosphonate vapor gas sensing. The synthesized composite also demonstrated excellent selectivity, stability, sensitivity, and rapid response time.