Comparative studies on MWCNTs, Fe2O3 and Fe2O3/MWCNTs thin films towards supercapacitor application

Abstract

An attempt has been made to synthesize multiwall carbon nanotubes (MWCNTs), Fe₂O₃, and Fe₂O₃/MWCNTs through a simple and cost-effective route onto a stainless steel (SS) substrate. The ‘dip and dry’ coating method was used for MWCNTs, whereas the successive ionic layer adsorption and reaction (SILAR) method was used for Fe₂O₃. Thin films were characterized using structural and surface morphological studies by XRD, FESEM and TEM. The results showed that hematite Fe₂O₃ nanoparticles with a particle size of less than 10 nm were uniformly coated onto the surface of MWCNTs. Comparative investigations have been made for MWCNTs, Fe₂O₃, and Fe₂O₃/MWCNTs as supercapacitive electrode materials with the aid of scan rate, cyclic voltammetry, charge–discharge studies, energy density, power density and stability. Among the three thin films, the Fe₂O₃/MWCNTs hybrid thin film electrode exhibited a high specific capacitance of 431 F g⁻¹ at a scan rate of 5 mV s⁻¹ and a high energy density of 38 W h kg⁻¹ with a power density of 800 W kg⁻¹ in 1 M Na₂SO₃ electrolyte solution. The detailed analyses are reported herein.