Enhanced photocatalytic and electrochemical performance of TiO2-Fe2O3 nanocomposite: Its applications in dye decolorization and as supercapacitors

This work reveals a green combustion route for the synthesis of TiO₂, Fe₂O₃ and TiO₂-Fe₂O₃ nanocomposites as photocatalysts for decolorization of Titan Yellow (TY) and Methyl Orange (MO) dyes at room temperature in aqueous solution concentration of 20 ppm under UV-light irradiation. We observed that the TiO₂-Fe₂O₃ nanocomposite shows superior photocatalytic activity for TY dye compared to pure TiO₂ and Fe₂O₃. Rate constant (k) values of TiO₂, Fe₂O₃ and TiO₂-Fe₂O₃ for TY and MO are 0.0194, 0.0159, 0.04396 and 0.00931, 0.00772 0.0119 kmin^-1 respectively. The surface area and pore volume of TiO₂-Fe₂O₃ nanocomposite were found to be 71.56 m²/g and 0.076 cm³/g, respectively as revealed by BET studies. From the Barrett-Joyner-Halenda (BJH) plot, the mean pore diameter of TiO₂-Fe₂O₃ nanoparticles was found to be 2.43 nm. Further, the TiO₂-Fe₂O₃ nanocomposite showed good electrochemical behavior as an electrode material for supercapacitors when compared to pure TiO₂ and Fe₂O₃ nanoparticles resulted in stable electrochemical performance with nearly 100% coulombic efficiency at a scan rate of 10 mV/s for 1000 cycles. Interestingly, the novelty of this work is that the designed supercapacitors showed stable electrochemical performance even at 1000^th cycle, which might be useful for rechargeable supercapacitor applications. The electrochemical properties of the nanocomposites were compared by the data obtained by cyclic voltammograms, charge-discharge tests and electrochemical impedance spectroscopic studies. These results demonstrated that the TiO₂-Fe₂O₃ nanocomposite showed stable performance compared to TiO₂ and Fe₂O₃ nanoparticles at current density of 5 Ag^-1.