Self-assembled flower-like iron oxide nanorod architectures as advanced anode material for electrochemical supercapacitors
摘要
Hierarchical and porous metal oxide-based anode materials have attracted considerable attention for use in high-performance supercapacitors, with increasing focus on carbon-free alternatives. In this work, we design low temperature assisted hydrothermal strategy for synthesizing hierarchical Fe₂O₃ nanoflowers with in-built nanorods, which serves as an effective anode material for aqueous supercapacitor. The structural and morphological properties were investigated, which shows 3D flower-like Fe₂O₃ comprising of interconnected nanorods (diameter of ∼30–50 nm; length of ∼250–300 nm), good crystallinity, high surface area, open porosity, and enhanced ion accessibility. When integrated onto Ni foam, these electrodes demonstrate pseudocapacitive behavior with a high specific capacitance of 487 F g⁻1 and capacity of 389.6 C g⁻1 at 4 mA cm⁻2 in 1 M Na₂SO₄. Electrochemical impedance spectroscopy reveals low charge transfer resistance (1.3 Ω), while long-term galvanostatic cycling confirms the good cycling stability of 85.2%. A hybrid charge storage mechanism of 3D flower-like Fe₂O₃ was quantified via power-law and kinetic analysis further reveals the significant capacitive- and diffusion-controlled contributions at high/lower scan rates. Furthermore, the fabricated symmetric supercapacitor showed maximum energy density of 12.7 Wh kg⁻1 with the power density of 1600 W kg and good cycling stability. These results underscore the potential of nanorod-in-built Fe₂O₃ nanoflowers as scalable, carbon-free anodes for next-generation aqueous supercapacitors.