Facile synthesis of nanosphere like rare-earth/transition metal dual-doped TiO₂ nanostructure for application as supercapacitor electrodes material

Nanostructured TiO₂ has been extensively used for environmental and energy storage applications because of its high chemical stability, economical, non-toxic, and significant charge density. However, the poor electrical conductivity of TiO₂ restricts its widespread practical application for high-performance supercapacitors. Hereby, in the present work, we investigated the influence of rare-earth/transition metal ions dual doping on electrochemical performance of TiO₂ by synthesizing Ti_0.90La_0.05M_0.05O₂ (M = Y, Nd, V) nanostructures via facile sol–gel method. The effect of dual doping on the prepared TiO₂-based nanostructures was studied for structural, electrical, and morphological characteristics by using XRD, FTIR, IV, and FESEM measurements. The XRD and FTIR results confirmed the successful dual doping with tetragonal phase formation of TiO_2, and FESEM images revealed the formation of interconnected nanosphere type morphology by La/V doping. The CV, GCD, LSV, and EIS were performed to assess the electrochemical behavior of grown TiO₂-based nanostructures for supercapacitor application. The electrochemical results exhibited the Faradic charge storage mechanism in all the fabricated nanostructures with pseudocapacitive nature. The CV results showed the highest specific capacitance (1070 F/g) for TiLaVO₂ nanostructure than other grown samples. TiLaVO₂ electrode also exhibited superior specific capacitance (803 F/g), energy density (28 Wh/kg), and power density (0.3 KW/kg), at a current density of 1 A/g in 1 M KOH electrolyte with better cycling stability 93% retention after 1000th cycle. The superior performance of TiLaVO₂ electrodes was attributed to the formation of nanospheres that offer more electroactive sites for ion/electron transportation, higher electrical conductivity (IV results), higher current density (LSV results), and lower resistance and fast charge transfer (EIS results). The dual doping of different ions provoked size tunability, electrical conductivity improvement, and superior electrochemical characteristics of TiO₂. Moreover, the facile strategy (dual doping) discussed in the present findings would provide insights for enhancing the electrochemical properties of TiO₂ for use as supercapacitor electrode material. Graphical abstract: [Figure not available: see fulltext.]