MnO2/TiN heterogeneous nanostructure design for electrochemical energy storage

MnO2/TiN nanotubes are fabricated using facile deposition techniques to maximize the surface area of the electroactive material for use in electrochemical capacitors. Atomic layer deposition is used to deposit conformal nanotubes within an anodic aluminium oxide template. After template removal, the inner and outer surfaces of the TiN nanotubes are exposed for electrochemical deposition of manganese oxide. Electron microscopy shows that the MnO2 is deposited on both the inside and outside of TiN nanotubes, forming the MnO2/TiN nanotubes. Cyclic voltammetry and galvanostatic charge–discharge curves are used to characterize the electrochemical properties of the MnO2/TiN nanotubes. Due to the close proximity of MnO2 with the highly conductive TiN as well as the overall high surface area, the nanotubes show very high specific capacitance (662 F g−1 reported at 45 A g−1) as a supercapacitor electrode material. The highly conductive and mechanically stable TiN greatly enhances the flow of electrons to the MnO2 material, while the high aspect ratio nanostructure of TiN creates a large surface area for short diffusion paths for cations thus improving high power. Combining the favourable structural, electrical and energy properties of MnO2 and TiN into one system allows for a promising electrode material for supercapacitors.