β-Co(OH)2–Co3O4/Graphene Oxide 3D-Nanoarchitecture modified electrode for electrochemical sensing and energy storage applications

Abstract

Cobalt-modified graphene oxide 3D-nanoarchitecture is fabricated here for its effective use as an electrode material for the sensing of rutin flavonoid and for supercapacitor applications. The graphene oxide preparation was accomplished here comparatively in a shorter period avoiding the tedious and time-consuming preparative pathways in other graphene-oxide-based systems. A sol-gel method was employed for hybridizing graphene with cobalt oxide/hydroxide. Material characterization studies revealed the coexistence of β-Co(OH)2 and spinel Co3O4 in the nanocomposite, whereas FESEM images revealed the 3D nanostructured morphology. The strong interaction between the carbon atoms of graphene sheets with the cobalt species is revealed from the XPS analysis. The synergistic effect provided a good current sensitivity of 1.68 μA/μM towards rutin sensing within a linear detection range of 0.1 μM–20 μM over Co(OH)2–Co3O4/graphene oxide (CoG) modified electrode. High selectivity is offered by the nanocomposite towards rutin and additionally, the sensor succeeded in the detection of a real sample, the rutin tablet. Repeatability and reproducibility in measurements are the added features of the CoG-modified electrode. The diffusion-controlled electrochemical behaviour over CoG was investigated using a redox probe K4[Fe(CN)6]. As a supercapacitor electrode material, the nanocomposite exhibited a maximum specific capacitance of 559.2 F/g at a scan rate of 10 mV/s and 288.4 F/g at 4 A/g current density. Also, it exhibited a high cyclic stability of 109.78% after 1800 continuous charge-discharge cycles displaying its excellence as an energy storage device. The nanocomposite exhibited a dominant contribution from EDLC towards the total capacitance with a low charge transfer resistance.