Crinum asiaticum-assisted green synthesis of TiO2 integrated Ti3C2-MXene@Ag composite electrodes for high-performance supercapacitors

Abstract

The present study reports fabrication and electrochemical investigations on a partly bio-derived ternary electrode, Ti3C2@Ag/TiO2 (MAT-3), in which TiO2 nanoparticles were green-synthesized from Crinum asiaticum leaf extract and are integrated with Ag-decorated Ti3C2-MXene. The Ag nanoparticles serve as conductive spacers that suppress restacking of Ti3C2-MXene sheets, while the green TiO2 contributes to redox-active sites and further inhibits restacking, raising the BET surface area more than six-fold over pristine Ti3C2-MXene. In 1 M H2SO4, the MAT-3 electrode delivers a specific capacitance of 255.87 F/g at 1 A/g, with lower charge-transfer resistance than its binary and pristine counterparts. Impedance analysis shows that this synergy translates into markedly faster charge-transfer kinetics: relative to pristine Ti3C2-MXene, the ternary electrode exhibits lower solution and a shorter relaxation time (0.318 s to 0.024 s), and a higher ion-diffusion coefficient, indicating efficient interfacial electron transport and rapid ionic access. A symmetric CR2032 cell retains 89.28% of its capacitance after 15,000 cycles at 98.49% coulombic efficiency, and three cells in series power a red LED for ∼8 min. The study underscores the potential of Ti3C2@Ag/TiO2 composite as a promising electrode material for supercapacitors.