Permselectivity and thickness-dependent ion transport properties of overoxidized polyaniline: a mechanistic investigation

Abstract

We report here the permselectivity of overoxidized polyaniline obtained using anodic polarization of polyaniline on glassy carbon electrodes. The contrasting redox behavior of overoxidized polyaniline coated electrodes towards [Fe(CN)] and [Ru(NH)] has been analyzed using cyclic voltammetry, hydrodynamic voltammetry and electrochemical impedance spectroscopy. This permselectivity vis a vis anion exclusivity arises from the incorporation of counter anions rather than by the formation of new functional groups in the polymer upon overoxidation - as inferred from FT Raman and UV-Visible spectral data. The surface charges of the polymeric films are also deduced from the zeta potential analysis. The thickness-dependent anion exclusion behavior of overoxidized polyaniline is quantitatively interpreted using diffusion coefficient measurements with rotating disc electrodes. The mechanism pertaining to the non-trivial role of film thickness in influencing anion exclusion is confirmed by additional impedance spectroscopy carried out during the overoxidation of polyaniline.

A binder‐free composite of graphite and kaolinite as a stable working electrode for general electrochemical applications

“…[ 22 ] The polymerization mechanism, kinetics, and electrochemistry of PANI have been revealed substantially in the prevailing literature. [ 23 ],[ 24 ] Therefore, the present work only provides information on the electrical and morphological features of PANI deposited on GKCE. PANI can successfully deposit on the working electrode surface (visible to bare eyes) with a series of ongoing scan cycles, which is reflected by the gradual increase in anodic/cathodic peak currents.…”

“…It is a well‐known fact that electropolymerization can result in various morphologies of PANI vastly depend on substrate type. [ 25 ] The previous investigations reported different PANI morphologies, exhibiting nanogranular structure/micrometer polymer particles, [ 24 ] sub‐micron particle network, [ 23 ] and interlinked porous network of micrometer size PANI fibers. [ 22,25 ] In contrast, PANI film deposited on the GKCE surface predominantly materialized with nanofibers (Figure 8).…”

“…[ 24,25 ] PANI‐GKCE consisting of nanofibers can significantly increase the electroactive surface area, resulting in a very high heterogeneous electron transfer rate (charge transfer resistance is inversely proportional to the heterogeneous electron transfer rate constant). [ 23,24 ] PANI‐GKCE exhibits relatively low charge transfer resistance (R CT ) due to facile electron transfer in comparison with PANI‐GC and PANI‐Pt (Table 4).…”

The polymeric conformational effect on capacitive deionization performance of graphene oxide/polypyrrole composite electrode

“…In conclusion, from the variation of ohmic resistance and redox capacitance responses between the two composite, it is reasonable to consider that the densely entanglement polymeric chain and the strong interactions arising from deep reduction, have greatly hindered the conformational transformation of PPy during the redox, which inclines to induce less doping level and more stabilizing polaronic structure of polymeric backbone. The conformational and electronic state structure characteristic not only is detrimental to the solid-phase electron transformation, but also will influence the ions intercalation/desintercalation in the electro-sorption-desorption cyclic process [33] . through linear regression [17] .…”

Hydrothermal Synthesis of Carbon Nanotubes-Polyaniline(CNT-PANI)Composites and Preliminary Electrochemical Characterization of CNT-PANI Coatings

“…Figure 4 shows the CV curves of GC electrode modified with NT1, and NTP1 to NTP4 coatings, respectively. Two oxidation peaks can be observed for the GC electrode modified with NTP2: one located at ~ 0.6 V and the other at ~ 1.8 V. The peak at 0.6 V could be attributed to the oxidation reaction of emeraldine (conductive form of PANI) in pernigraniline, while the 1.8 V peak may be due to the slow transfer of electrons between the two forms of PANI (emeraldine-pernigraniline) caused by the steric hindrance of the polymer chain ( Figure 5) [15,16]. 5.…”