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 μm. 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.