Sn–Co Co‐Doped α‐Fe ₂ O ₃ Nanostructures for Enhanced Supercapacitor Applications

Abstract High‐performance and cost‐effective Sn–Co co‐doped α‐Fe 2 O 3 nanostructures were synthesized using a hydrothermal method and evaluated for their suitability as electrode materials in supercapacitor applications. Structural and morphological features were analyzed by X‐ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), while energy‐dispersive X‐ray spectroscopy (EDAX) confirmed the homogeneous elemental distribution. Raman spectroscopy indicated doping‐induced variations in the A 1g and E g vibrational modes of α‐Fe 2 O 3 . The successful integration of Sn⁴⁺ and Co 2 ⁺ ions into the hematite crystal structure were confirmed through X‐ray photoelectron spectroscopy (XPS) and analysis of the unit cell expansion, attributed to the substitution of Fe 3 ⁺ ions with larger Sn⁴⁺ and Co 2 ⁺ ions in octahedral coordination sites. Electrochemical characterization in a three‐electrode configuration with 3.0 M KOH electrolyte demonstrated remarkable improvements in charge storage performance. Cyclic voltammetry (CV) revealed well‐defined Faradaic redox activity with excellent reversibility at higher scan rates. The specific capacitances of pristine, Co‐doped, and Sn–Co co‐doped α‐Fe 2 O 3 electrodes were determined to be 44.17, 153.51, and 1427 Fg −1 , respectively. Galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) further confirmed enhanced stability, reduced resistance, and superior rate capability. These findings demonstrate that Sn–Co co‐doped α‐Fe 2 O 3 nanostructures are promising low‐cost electrode materials for advanced supercapacitor applications.