Strategic intercalation of AB2O4 perovskite oxides for synergetic enhanced redox activity in sulphonated Ti3C2Tx MXene for energy storage applications†

Flexible supercapacitors have emerged as efficient and fast energy storage devices for new generation electronics. Two-dimensional (2D) transition metal carbides (MXene) have garnered attention as supercapacitor electrodes owing to their conductive layered sheets and the tunability of their surface functional groups. In the present work, the Ti₃C₂T_x MXene surface was sulphonated using dimethyl sulfoxide (DMSO) and intercalated with AB₂O₄ (A = Co and Ni; B = Fe) perovskite nanoparticle (NPs). The sulphonated MXene (TMS) was processed using a sonication method in DMSO solvent to enhance the surface area and redox active sites for electrolyte (0.1 M H₂SO₄) interaction. The redox dominated enhancement in specific capacitance was observed in 3 wt% CoFe₂O₄ (CFO)-intercalated TMS (3CTMS) and 3 wt% NiFe₂O₄ (NFO)-intercalated TMS (3NTMS), as confirmed by Electrochemical Impedance Spectroscopy (EIS) and Dunn's method analysis. The specific capacitance of 3CTMS was found to be 593.81 F g⁻¹ at 5 mV s⁻¹, with an excellent cyclic stability of 81.75% after 10 000 cycles. A flexible symmetric supercapacitor fabricated with 3CTMS showed an energy density of 4.177 W h kg⁻¹ and a power density of 512.17 W kg⁻¹. The flexible supercapacitor has been utilized in real time applications by charging and discharging to power 5 Light-Emitting Diodes (LEDs) with different forward voltages.