Fabrication and supercapacitor behavior of phosphomolybdic acid/polyaniline/titanium nitride core–shell nanowire array

Abstract

Phosphomolybdic acid (PMo₁₂) with reversible electron shuttling is a potential electrode material. Possessing good solubility limits its applications in energy storage. A novel and efficient phosphomolybdic acid/polyaniline/titanium nitride core–shell nanowire array (PMo₁₂/PANI/TiN NWA) was synthesized as a supercapacitor electrode. FT-IR and Raman spectra showed that PMo₁₂ was well incorporated into PANI and the structures of PANI and PMo₁₂ were completely retained. PMo₁₂/PANI/TiN NWA displayed core–shell nanowire array morphology with narrow diameters and oriented perpendicular to the substrate, benefiting ion diffusion and electron transportation. The PMo₁₂/PANI/TiN NWA electrode exhibited a higher specific capacitance of 469 F g⁻¹ at 1 A g⁻¹ compared with PANI/TiN NWA electrode. PMo₁₂/PANI/TiN supercapacitor could achieve a specific capacitance of 69 F g⁻¹ and an energy density of 21.6 W h kg⁻¹ at a current density of 0.5 A g⁻¹ and an output voltage of 1.5 V. The effects of PMo₁₂ incorporated in PANI and the immobilization mechanism of PMo₁₂ are proposed and discussed.