The composites of carbon nanotube (CNT) supported by Sn-doped MnO2 with enhanced capacitance have been fabricated with varying dopant concentrations. The composites have been subjected to physiochemical, configurational, and morphological analyses by FTIR, UV–Vis spectroscopy, X-ray diffraction and field emission scanning electron microscopy, high resolution transmission electron microscopy and selected area electron diffraction studies. The electrochemical performance of the composite has been evaluated by cyclic voltammetry and charge/discharge techniques. Highest specific capacitances of 940 F g−1 at a current density of 0.35 A g−1 and 927 F g−1 at 5 mV s−1 in 1 M Na2SO4 electrolyte solution was achieved in the case of 5% Sn doped composite. Moreover, the electrode demonstrated good cycling performance and retaining 79.7% of the initial capacitance over 3000 cycles. The superior electrochemical performance is accredited mainly to the porous sheath hierarchical architecture, which consist of inter connected MnO2 nanoneedles uniformly coated over the CNT surface. This peculiar architecture is responsible for fast ion/electron transfer and easy access of the active material.

Abstract
    1 Introduction
    2 Experimental
        2.1 Materials
        2.2 Synthesis of composites
        2.3 Characterizations
        2.4 Electrochemical test
    3 Results and discussion
        3.1 FTIR-spectrum
        3.2 UV–visible analysis
        3.3 XRD analysis
        3.4 Morphology of composites
        3.5 Cyclic voltammetric
        3.6 Charge–discharge studies
    4 Conclusion
    Acknowledgements 
    References

• Indu Kaushal(Thin Film Laboratory, Department of Materials Science and Nanotechnology, Deenbandhu Chhotu Ram University of Science and Technology)
• Ashok K. Sharma(Thin Film Laboratory, Department of Materials Science and Nanotechnology, Deenbandhu Chhotu Ram University of Science and Technology)
• Priya Saharan(Thin Film Laboratory, Department of Materials Science and Nanotechnology, Deenbandhu Chhotu Ram University of Science and Technology)
• Vinit Kumar(Thin Film Laboratory, Department of Materials Science and Nanotechnology, Deenbandhu Chhotu Ram University of Science and Technology)
• Surender Duhan(Thin Film Laboratory, Department of Materials Science and Nanotechnology, Deenbandhu Chhotu Ram University of Science and Technology)