Surface-induced changes in the vibrational spectra of conducting polymer - carbon nanotube hybrid materials

We present infrared (IR) and Raman spectra of carbon nanotubes (CNTs) coated by the conducting polymers polyaniline (PANI), polycarbazole (PCz), and melanin (polydopamine). These hybrid materials have been prepared by electrochemical polymerization and exhibit increased conductivity and enhanced electron transfer from the electrolyte to the electrode. Interaction of the polymers with the nanotube surface causes attenuation of some IR modes [surface-attenuated infrared absorption (SAIRA) effect], while the Raman modes are enhanced by a surface-enhanced Raman scattering (SERS) mechanism. The magnitude of the attenuation depends on the strength of the nanotube-polymer interaction. We compared the spectra of the hybrids and found the most outspoken effect in the case of polyaniline, in accordance with the results of ultraviolet-visible (UV-Vis) and impedance spectroscopy.