Building up nanostructured layer-by-layer films combining reduced graphene oxide-manganese dioxide nanocomposite in supercapacitor electrodes

Highlights: • Incorporation of MnO₂ nanostructures into reduced graphene oxide (rGO) sheets. • rGO-MnO₂ nanostructured layer-by-layer (LbL) film for supercapacitor application. • Areal capacitance with an order of magnitude higher (mF/cm²) than usual. • High capacitive retention performance of 99% and high charge-discharge time. • Superior performance compared with other reported rGO-MnO₂ systems. Research on nanocomposites is essential to achieve supercapacitors with enhanced performance for energy storage. In that regards, carbon materials and metal oxides have been employed in conjunction to yield supercapacitors with improved properties. Here we present the fabrication of a layer-by-layer (LbL) film containing manganese dioxide (MnO₂) nanostructures embedded into reduced graphene oxide (rGO) sheets and arranged with poly(allylamine-hydrochloride) (PAH) for supercapacitor application. While scanning electron microscopy images confirm the incorporation of MnO₂ nanostructures into the rGO layers, cyclic voltammetry and galvanostatic charge-discharge measurements reveal the electrocapacitive features of the films. Nanostructured PAH/rGO-MnO₂ LbL films containing 20 bilayers lead to a supercapacitor with high areal capacitance of ca. 112 mF/cm² at 1 mV/s and 460 F/g at 1 A/g, in addition to a high capacitive retention performance of 99% over 10,000 cycles and a high charge-discharge time of ca. 600 s. Such properties demonstrate, therefore, the PAH/rGO-MnO₂ LbL film a promising architecture to be further explored in energy storage nanostructured systems.