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

Abstract

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 wellbalanced 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.