Synthesis of polyaniline nanostructures by electrochemical deposition on niobium

Nanostructured polyaniline films have been electrochemically synthesized on passivated niobium substrate by potentiodynamic method in 0.5 and 1 mol L−1 H2SO4 solution and different aniline/acid molar ratios. The niobium oxide particles formed during passivation induce the nucleation of polyaniline nanofibers via adsorbed phenazine nucleates. The infrared spectra of polyaniline nanofibers showed the presence of vibrations attributed to phenazine-units in the polymer chain which support the phenazine nucleates theory for polyaniline nanofiber growth. The morphology of polyaniline is also influenced by acid concentration and a branched structure consisting of polyaniline nanofibers with a mean diameter of 70 nm is observed for 1 mol L−1 sulfuric acid solution. The shape of the impedance spectra is controlled by charge transport through ion diffusion, with higher diffusion resistances for granular polyaniline. The capacitance increases with the polymer layer thickness and has higher values for nanofibrilar than for granular polyaniline.