MnO2 encapsulated electrospun TiO2 nanofibers as electrodes for asymmetric supercapacitors.

We report a facile technique to fabricate manganese dioxide (MnO2) encapsulated titanium dioxide (TiO2) nanofiber heterostructure for its use as an electrode material in aqueous electrolyte based asymmetric supercapacitor (SC). MnO2 coated TiO2 nanofibers, prepared by electrospinning and post-hydrothermal process exhibited superior electrochemical properties in aqueous Na2SO4 electrolyte. The MnO2 shell with average thickness of approximately 10 nm contributed to the high electrochemical performance for charge storage by redox reaction and intercalation mechanisms, while the anatase phase TiO2 core provided an easy pathway for electronic transport with additional electrochemical stability over thousands of charge-discharge cycles. An asymmetric SC designed from the MnO2-TiO2 nanofiber electrode and single walled carbon nanotubes electrode showed high operating voltage window (2.2 V) with maximum gravimetric capacitance of 111.5 F g-1.