Layer-by-Layer Films of Graphene Oxide–MnO₂–NbO₂ for Nanostructured Energy Storage Applications

The rational integration of nanomaterials into well-defined architectures has proven effective in enhancing charge storage for electrochemical energy devices such as supercapacitors. In this study, we developed layer-by-layer (LbL) nanostructured films composed of graphene oxide (GO), manganese dioxide (MnO2), and niobium dioxide (NbO2), assembled with a polyethylenimine (PEI) matrix, to serve as advanced electrodes for supercapacitors. The multilayered films, fabricated with up to 20 bilayers, exhibited uniform morphology, high surface area, and interconnected pathways favorable for ion transport and charge storage. Electrochemical characterization revealed a high specific capacitance of 353.0 F g–1 and an specific energy of 24.0 Wh kg–1, outperforming analogous single-oxide systems based on GO with either MnO2 or NbO2. The LbL films also maintained 97.5% of their initial capacitance after 10,000 charge/discharge cycles, underscoring their structural robustness and electrochemical stability. Furthermore, the system demonstrated biointegration capability upon immobilization of glucose oxidase (GOx), introducing bioelectrocatalytic activity while preserving capacitive behavior─a key step toward biosupercapacitor applications. These findings highlight the synergistic effects of the hybrid oxide components and the versatility of the LbL method for designing multifunctional energy storage platforms with potential use in emerging tecnologies, such as wearable electronics, self-powered IoT devices, and bioelectronic diagnostics.