PPy wrapped MnO2@C/TiO2 nanowire arrays for electrochemical energy storage.

Herein, Polypyrrole was used as the conductive wrapping material electro-deposited on the MnO 2 nanoflakes covered on C/TiO 2 nanowire arrays to form PPy@MnO 2 @C/TiO 2 double shell/core structured arrays electrode for supercapacitor. Their structure and surface morphology were studied by using X-ray diffraction analysis, scanning electron microscopy and transmission electron microscopy. The results suggest that a thin layer of PPy was successfully wrapped on the surface of MnO 2 , and the shell/core structure of MnO 2 @C/TiO 2 nanowire arrays was not changed after electro-deposition of PPy. The electrochemical tests indicate that the PPy@MnO 2 @C/TiO 2 double shell/core arrays electrode exhibits high specific capacitance of 715 F g −1 at a charge/discharge current density of 1 A g −1 and improved specific capacitance retention to 84.0% after 1000 cycles. These results show that the unique three dimensional (3D) double shell/core structured electrode holds promise for high-performance energy storage devices. The superior capacitive perfomance may due to the unique 3D C/TiO 2 nanowires and the unique double shell/core structures. Firstly, the 3D C/TiO 2 nanowire arrays, as excellent platform for loading active materials, can facilitate the permeation of electrolyte. Moreover, the thin layer PPy tightly wrapped on the MnO 2 nanoflakes can improve the electrical conductivity of MnO 2 . Therefore, the PPy@MnO 2 @C/TiO 2 electrode is promising candidate for electrochemical energy applications. [ABSTRACT FROM AUTHOR]