Hexagonal Co3O4 anchored reduced graphene oxide sheets for high-performance supercapacitors and non-enzymatic glucose sensing

Abstract

Reduced graphene oxide (RGO) incorporated onto metal–organic framework (MOF)-derived Co₃O₄ hexagons is prepared via a hydrothermal route for supercapacitor and glucose sensor applications. Various analysis techniques demonstrate that the Co₃O₄ hexagons were uniformly spread over the thin graphene sheets to assist the electron accessibility of the electrode materials. Under optimized conditions, using 0.1 M KOH electrolyte at a current density of 4 A g⁻¹, a specific capacitance value of 1300 F g⁻¹ is obtained. The fabricated asymmetric supercapacitor cycled reversibly and exhibits high energy and power density values of 65.8 W h kg⁻¹ and 2048 W kg⁻¹, respectively, over the voltage range of −0.1 V to 0.4 V. The asymmetric supercapacitor shows 80.5% capacitance retention even after 5000 cycles at a current density of 4 A g⁻¹, which indicates its high cycling stability in view of the fact that it is binder-free. Furthermore, the RGO–Co₃O₄ hexagon-modified electrode was optimized to realize the reliable amperometric determination of glucose concentration with a very low detection limit and excellent sensitivity value of 0.4 μM and 1.315 mA mM⁻¹ cm⁻², respectively. All of these remarkable performance indicators suggest that RGO–Co₃O₄ is a promising electrode material for next-generation energy storage devices and electrochemical sensors.