In-situ carbon-coated iron oxide (ISCC-Fe3O4) as an efficient electrode material for supercapacitor applications

Transitional metal oxides (such as iron oxides) hold significant potential as electrode materials for supercapacitors due to their promising properties, such as high specific capacitance, multiple oxidation states, high energy density, abundance, and versatile synthesis methods. However, challenges such as poor rate performance, low electrical conductivity, and limited cycling stability must be addressed to make these materials viable for practical applications. To enhance the performance of transitional metal oxides in supercapacitors, carbon materials (graphene, carbon nanotubes, activated carbon, etc.) have been employed effectively. Among transition metal oxides, iron oxide (Fe 3 O 4 ) is abundant in nature and low cost, making it an attractive material for scalable and cost-effective supercapacitor production. In this study, in-situ-carbon-coated iron oxide (ISCC-Fe 3 O 4 ) was synthesized using glucose as a carbon precursor, which transformed into conducting carbon through heat treatment at 1200°C. ISCC-Fe 3 O 4 was used as an electrode material. Brunauer-Emmett-Teller (BET) analysis revealed that the surface area and average pore diameter of ISCC-Fe 3 O 4 were 36.3 m 2 /g and 4.5 nm respectively, indicating the nanosized particles and multi-porous structure. X-ray diffraction (XRD), Raman spectroscopy, and electron microscopy (TEM) analysis of ISCC-Fe 3 O 4 confirmed the presence of carbon coating on the surface of iron oxide particles. ISCC-Fe 3 O 4 exhibited a specific capacitance of 150 F/g at 1.5 A/g (170.6 F/g at 25 mV/s) and achieved an energy density of 20.8 Wh/kg at a power density of 745.1W/kg in a 1M Na 2 SO 4 electrolyte. The multi-porous structure of ISCC-Fe 3 O 4 (as confirmed by BET and scanning electron microscopy (SEM)) may allow sufficient diffusion of electrolyte and increase the surface area for interfacial redox reactions in supercapacitors, while the carbon produced from glucose provides a uniform conductive network essential for efficient charge transport and structure stability in the supercapacitor.