Effect of oxidant on electronic transport in polypyrrole nanotubes synthesized in the presence of methyl orange
Abstract
Polypyrrole nanotubes with diameter 60-400 nm are synthesized with methyl orange as template and various oxidants, iron(III) chloride hexahydrate, iron(III) sulfate hydrate, and ammonium peroxydisulfate. The highest electrical conductivity of compressed pellets, 66 S cm(-1), is found for iron(III) chloride.
Regions with 3D variable range hopping in series with ordered regions near metal-insulator transition govern the charge transport. Other oxidants and globular morphology provide less conducting samples, <10 S cm(-1).
The transport mechanism is identified with the heterogeneous model of tunneling between (bi)polaronic clusters with parallel contribution of Arrhenius-like activated conductivity. The results of conductivity are correlated with the protonation level reflected in the infrared spectra and with the ratio of bipolaron/polaron bands revealed by Raman spectroscopy.