Facile synthesis of ultrathin and perpendicular NiMn₂O₄ nanosheets on reduced graphene oxide as advanced electrodes for supercapacitors

Ultrathin nickel manganese oxide nanosheets grown vertically on reduced graphene oxide (NiMn₂O₄ NSs@rGO) were successfully fabricated through a facile co-precipitation and thermal treatment process. Such a unique nanostructure can not only facilitate electron transfer and electrolyte penetration but also withstand the structural damage of the active materials in electrochemical reactions. The resulting product NiMn₂O₄ NSs@rGO was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) analysis. When evaluated for its potential as an electrode material in supercapacitors, the as-synthesized NiMn₂O₄ NSs@rGO nanocomposite exhibits enhanced energy storage performance with high specific capacitance (1243 F g^-1 at 3 A g^-1) and prominent cycle life (80.8% capacitance retention after 5000 cycles). These results indicate that the ultrathin and perpendicular NiMn₂O₄ nanosheets with rGO substrates obtained from this green and facile route hold great prospects in high performance supercapacitor applications.