Tin (Sn)-doped hematite (a-SnxFe2-xO3) nanostructures as high-performance electrodes for supercapacitor application

Doped metal oxide nanostructures have emerged as a subject of considerable interest in the domain of energy storage applications, owing to their exceptional characteristics in comparison to their pristine metal oxides. Herein, pristine and Tin (Sn) doped hematite (a-Fe2O3) nanostructures were successfully synthesized using the hydrothermal method. The effect of Sn doping on various characteristics of hematite nanoparticles, such as unit cell size, crystallinity, particle size, and electrochemical properties, was examined and analyzed. The verification of Sn4+ ions being integrated into the crystalline structure of hematite was established through X-ray photoelectron spectroscopy (XPS) and with the assessment of unit cell expansion resulting from the substitution of octahedrally coordinated Fe3+ ions, with notably larger Sn4+ ions. The electrochemical properties of the materials that were prepared were analyzed within a three-electrode cell setup, utilizing a 3.0 M aqueous potassium hydroxide electrolyte. Notably, the hematite electrode doped with 7% Tin exhibited exceptional capacitance, reaching a value of 833 F/g at a scan rate of 10 mV/s. The incorporation of Tin into the hematite structure played a critical role in facilitating efficient ion transport and enhancing conductivity, thus promoting favorable conditions for various electrochemical reactions. Furthermore, the material exhibits exceptional rate capability and robust cycling stability. Finally, an asymmetric supercapacitor was fabricated by integrating Sn-doped a-Fe2O3 as the anode material and activated carbon as the cathode material. The resultant device showcases impressive energy and power densities of 28.3 Wh Kg(-1) and 528.8 W Kg(-1), respectively. Such noteworthy performance characteristics signify its promising prospects for practical implementation in energy storage devices.