Ternary nanocomposite of polyaniline/manganese dioxide/titanium nitride nanowire array for supercapacitor electrode

The electroactive polyaniline (PANI) and manganese oxide (MnO2) were integrated with titanium nitride (TiN) nanowire array (NWA) to form PANI/MnO2/TiN ternary nanocomposite for supercapacitor application. TiN NWA was prepared via a seed-assisted hydrothermal synthesis and ammonia nitridization process. The electroactive MnO2 and PANI was layer-by-layer coated on TiN NWA to form heterogeneous coaxial structure through a stepwise electrodeposition process. Scanning electron micrographs revealed that the well-separated TiN NWA was composed of well-distributed nanowires with diameters in the range of 10-30 nm and a total length of 1.5 mu m. A villiform MnO2 layer with a thickness of 10-20 nm covered on TiN NWA to form MnO2/TiN NWA composite. The coral-like PANI layer with thicknesses in the range of 20-50 nm covered on the above MnO2/TiN NWA to form PANI/MnO2/TiN NWA. Electrochemical measurements showed that a high specific capacitance of 674 F g(-1) at a current density of 1 A g(-1) (based on total mass of PANI/MnO2) was obtained for PANI/MnO2/TiN NWA ternary nanocomposite, which was much higher than that of PANI/MnO2/carbon-cloth composites reported previously. This ternary nanocomposite also showed a good rate and cycling stability. Moreover, in comparison with PANI/TiN NWA or MnO2/TiN NWA, the specific capacitance of PANI/MnO2/TiN NWA was obviously enhanced due to the extra pseudocapacitance contribution and the effective surface area of coral-like PANI layer, showing the advantage of manipulating the heterogeneous coaxial configuration between PANI and MnO2 for fundamentally improved capacitive performance. These results demonstrated that PANI/MnO2/TiN NWA ternary nanocomposite was a promising candidate electrode material for supercapacitor application.