Fe-doped chitosan@SiO₂ hybrid as a sustainable biomacromolecular electrode for high-performance supercapacitors

In this study, a novel eco-friendly electrode material was developed by utilizing the renewable biopolymer chitosan as the primary framework, reinforced with iron ions and silica nanoparticles (Fe-doped chitosan@SiO₂). Chitosan, derived from natural biomass, offers abundant amino and hydroxyl functional groups that facilitate strong coordination with iron species and uniform anchoring of silica, leading to a robust porous network with enriched electroactive sites. Comprehensive physicochemical analyses, including SEM, TEM, XRD, FTIR, BET, and XPS, confirmed the successful incorporation and homogeneous dispersion of Fe and SiO₂ within the chitosan matrix, resulting in a higher surface area and improved electrical conductivity. Electrochemical performance was systematically investigated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy in different aqueous electrolytes (NaOH, Na₂SO₄, and H₂SO₄). The Fe-doped chitosan@SiO₂ electrode exhibited an outstanding specific capacitance of 404 F g^-1 at a current density of 0.2 A g^-1 in acidic medium, significantly surpassing that of pristine chitosan. Moreover, it demonstrated excellent cyclic stability, maintaining 87.6 % of its initial capacitance after 5000 charge-discharge cycles. The incorporation of Fe notably reduced charge-transfer resistance, as evidenced by EIS, while Ragone plot analysis confirmed a well-balanced energy and power density. These findings highlight the promising potential of biomass-derived chitosan as a sustainable platform for the design of high-performance pseudocapacitive materials.