Synergistic design of high-performance symmetric supercapacitor based on iron oxide nanoplatelets/COOH-MWCNTs heterostructures: DFT computation and experimental analysis

Abstract

Here, we employed facile methods to develop a symmetric supercapacitor based on a heterostructure consisting of iron oxide (III) (hematite) nanoplatelets dispersed on carboxyl-functionalized multiwalled carbon nanotubes (Fe2O3/COOH-MWCNTs). The Fe2O3/COOH-MWCNTs supercapacitor effectiveness was evaluated using a 3-electrode system, demonstrating an outstanding specific capacitance of 250 F/g at 1 A/g and preserved 98.41% of its capacitance after 5000 cycles, indicating excellent cycling stability. Moreover, the symmetric Fe2O3/COOH-MWCNTs device achieved an ultrahigh energy density of 44 Wh/kg while maintaining a power density of 325 W/kg, showcasing its capability to provide substantial energy output. Furthermore, we employed Density Functional Theory (DFT) to determine the quantum capacitance of Fe2O3, both with and without functionalized-MWCNTs. These results were utilized to assess the impact of functionalized MWCNTs on enhancing the energy storage performance of the heterostructures, as well as estimating the double layer capacitance in these structures.