Electrochemical capacitance of polypyrrole–titanium nitride and polypyrrole–titania nanotube hybrids

Abstract

Both polypyrrole–titanium nitride (PPy–TiN) and polypyrrole–titania (PPy–TiO₂) nanotube hybrids have been prepared by incorporating electroactive polypyrrole into well-aligned titanium nitride and titania nanotube arrays through a normal pulse voltammetry deposition process. Microstructure characterization shows that the polypyrroles have been fully coated on the titanium nitride and titania nanotube arrays to form coaxial heterogenous nanohybrids. The galvanostatic charge–discharge measurements indicate that the PPy–TiN and PPy–TiO₂ nanotube hybrids have specific capacitances of 1265 and 382 F g⁻¹ at a current density of 0.6 A g⁻¹. Both nanotube hybrids have similar cyclability, exhibiting stable capacitances of 459 and 72 F g⁻¹ after 2000 cycles at a high current density of 15 A g⁻¹. The highly conductive titanium nitride substrate can promote the electrochemical capacitance of polypyrrole more significantly, as compared to the titania semiconductor, contributing to a higher supercapacitance performance of PPy–TiN. This indicates that PPy–TiN nanotube hybrids can be more suitable to act as supercapacitor electrode materials.