Hydrothermal synthesis of nanocages of Mn-Co Prussian blue analogue and charge storage investigation of the derived Mn-Co oxide@/rGO composites

Abstract

Prussian blue analogues (PBA) and their derived materials are intriguing for energy storage platforms due to the intrinsic open framework, tunable composition, low cost, and easy preparation. In recent years, current research has focused on improving their conductivity and energy storage. In this paper, cobalt-manganese Prussian blue analogues (PBA) were hydrothermally synthesized as self-assembly on graphene oxide. The obtained intermediate was precisely heat-treated to produce Co-Mn oxide nanocages on reduced graphene oxide (Mn-Co oxide/rGO). The as-prepared composite was characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectrometry (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX), Raman Spectroscopy, transmission electron microscopy (TEM), Thermogravimetric analyzer (TGA), and Brunauer-Emmett-Teller (BET) surface area analysis. It had been discovered that the interaction between the carbon and the Co-Mn Oxide not only prevents the agglomeration and significantly maximizes the surface, but also provides a network of conductive surface for quick electron transport resulting in an effective electrical transmission path and improved ionic absorbability and conductivity. The Mn-Co oxide @rGO nanocomposite delivers a maximum specific capacitance of 809 Cg−1 in 3 M KOH aqueous electrolyte at a high current density of 1 A g−1. After 4000 cycles at 20 A g−1 current density, the nanocomposite had preserved 86% of its starting capacitance. A two-electrode asymmetric cell (ASC) was designed and tested for electrochemical performance using Mn-Co oxide @ rGO as the positive electrode and activated carbon (AC) as the negative electrode. The designed device works excellently, with a maximum energy and power density of 55.55 Wh kg−1 and 972.73 W kg−1 in 1 A g−1, respectively.