Facile synthesis of TNT-VO2(M) nanocomposites for high performance supercapacitors

In this work, we report the synthesis of titania nanotube (TNT) -VO2(M) nanocomposites through a combined potentiostatic anodisation-hydrothermal procedure and its application in supercapacitors. Structural, morphological and chemical characterisations were done by XRD, FE-SEM and XPS analyses and electrochemical characterisations were done by CV, GCD and EIS. The TNT-VO2(M) nanocomposites exhibited very high capacitive performance as compared to their individual components, due to the synergistic contribution from both. Altered morphologies for composites were obtained at varying hydrothermal temperatures under similar conditions. The TNT-VO2(M) nanocomposite which is formed at 180 °C, TNT-V180 with VO2(M) nanorings over TNT showed the best CV performance in three electrode configuration with specific capacitance values ~152.21 mFcm−2 at scan rate 5 mVs−1 and confirmed by GCD and EIS. The open porous morphology with maximum available surface aided more charge accumulation at the electrode-electrolyte interface and better redox interaction with electrolyte ions resulting in its unique synergistic capacitive behaviour compared to others. The asymmetric supercapacitor fabricated with TNT-V180 as the negative electrode and active carbon (AC) as the positive electrode delivered a very high specific capacitance of 246.67 mFcm−2 with an ultra-high energy density of 111 μWhcm−2 at 180 μWcm−2 power density. [Display omitted] •TNT- VO2(M) nanocomposites were prepared by successive anodisation-hydrothermal methods for supercapacitor applications.•SEM images show diverese morphologies for VO2(M) formed on TNTAs under varying hydrothermal temperatures.•Capactive performance were analysed by CV, GCD and EIS techniques.•Composites of VO2(M) nanorings exhibits superior performance owing to its open porous morphology.•Assembled capacitor delivered a high capacitance of 246.67 mF/cm2 with an ultra high energy density.