V. V. Abalyaeva

The composites of polyaniline with multiwall carbon nanotubes: Preparation, electrochemical properties, and conductivity

Composite materials based on the multiwall nanotubes (content in the material from 1 to 65 wt %) and polyaniline are prepared and characterized. The composite materials are prepared by four methods: chemical synthesis, electrochemical synthesis, mixing of dry components, and mixing of solutions with subsequent removal of solvent. The results of calculations of the specific capacity of the composite materials, as well as their conductivity, stability, and behavior under the conditions of charging-discharging point out to their applicability in devices for the energy storage. The range of critical changes in the values of specific capacity and conductivity falls into the interval of the multiwall nanotubes content in the composite from 5 to 25 wt %. The composite materials preparation methods used in this work enable one to choose an appropriate composite preparation method reasoning from the final purpose of its application (obtaining of high capacity or conductivity). The carbon nanotubes, the body of the composite, with their stable electronic conduction, can sustain the composite’s electrical conductivity at reasonable level irrespective of the properties of the second component (polyaniline) in the case in question.

Preparation and study of polyaniline-and multiwall-carbon-nanotube-based composite materials

Polyaniline (PANI)-based composite materials containing 5 to 65 wt % of multi-wall carbon nanotubes (MCNT) are prepared. Their electrochemical characteristics are studied, in particular, the effect of the MCNT content in the composite on the composite and PANI specific capacitance. The increase in the composite capacitance, as well as the capacitance of the PANI being part of the composite, varies over the range from 5 to 25 wt %. This MCNT content is optimal for the preparing of a new MCNT-and PANI-based composite material. Over the above-given range, the increase in capacitance and the improving of conductivity are compromised at best. For a set of samples with varying MCNT content, the conductivity curve practically replicates the capacitance curve. The critical conductivity changes fall practically into the same range (5–30 wt %).

Synthesis and electrochemical behavior of polyaniline doped by electroactive anions

Electrochemical potentiodynamic and potentiostatic synthesis was used to obtain polyaniline (PANI) doped by new electroactive anions (EAAs): organic dianion of the diammonium salt of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfoacid) (ABTS) and inorganic ammonium hexachloroiridate dianion IrCl62− (HCI). Two methods of electrochemical synthesis were studied: under constant potential (potentiostatic synthesis) and under potential cycling (potentiodynamic synthesis). The optimum ratio of EAA: principal electrolyte (1 M H2SO4) was found at which the maximum catalytic effect was obtained in the course of the synthesis and the principal properties of PANI obtained were preserved.

Electrochemical properties of polyaniline film doped by Ce3+ cation

Electrochemical Synthesis (ES)of polyaniline (PAni) is carried out in the presence in electrolyte (1 M H2SO4) of cerium (III) sulfate under potentiostatic and potentiodynamic modes. It is shown that Ce3+ cations in electrolyte catalyze ES, i.e. accelerate both ES variants. The obtained polymers were characterized using the scanning electron microscopy (SEM) technique and also on the basis of the calculation of electrochemical characteristics. Relaxation in PAni polymers doped by the Ce3+ cation occurs several times faster than in proton-doped PAni. The minimum change in ΔE and E is observed in polymers doped by Ce3+ cations during the electrochemical cycling of PAni and PAni-Ce at high rates.

Regularities of electrochemical behavior of polyaniline doped by electroactive anions

Electrochemical potentiodynamic and potentiostatic synthesis is used to obtain polyaniline (PANI) modified by new electroactive anions: organic dianion of the diammonium salt of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfo acid) (ABTS) and inorganic ammonium hexachloroiridate dianion IrCl62− (HCI). Electrochemical behavior of the modified PANI-ABTS and PANI-HCI polymers is studied by means of the meth ods of cyclic voltammetry (CV) and charge-discharge dependences. It is shown that modified PANI-ABTS and PANI-HCI remain electroactive at much higher potential sweep rates as compared to PANI doped by HSO4− (PANI-sulfo). Electrochemical capacity values are calculated on the basis of the data of CVs and discharge curves and coulombic efficiency of the new polymers that exceeds significantly the corresponding values for PANI-sulfo. This effect is enhanced when the ABTS and HCI additives are introduced into the supporting electrolyte in all electrochemical processes.

Effect of electroactive anions on electrochemical behavior of polyaniline

Electrochemical potentiostatic synthesis was used to obtain polyaniline (PAni) modified by new electroactive dopants: dianions of a diammonium salt (2,2′-azine-bis-(3-ethylbenzthiazoline-6-sulfoacid) (ABTS) and ammonium hexachloriridate IrCl62− (HCI). Electrochemical behavior of PAni-ABTS and PAni-HCI modified polymers is studied by means of the methods of cyclic voltammetry (CV) and measuring charge-discharge dependences. It is shown that modified PAni-ABTS and PAni-HCI remain electroactive at significantly higher potential sweep rate dependences as compared to PAni doped by HSO4− (PAni-sulfo). Electrochemical capacity values C are calculated according to the CV data (F/g) and discharge curves (mA h/g) and coulombic efficiency values (ή) of new polymers are determined that cause a considerable increase in the pertinent characteristics of PAni-sulfo. This effect is enhanced in the case of introducing the ABTS and HCI additives into the background electrolyte.

Polyaniline electrode for assaying antioxidants

It is shown that an electrochemical sensor for determining concentration of antioxidants in various solutions and mixtures can be created. An organic or inorganic oxidant introduced into electrosynthesized polyaniline interacts with antioxidants in solution at a specified potential. The antioxidant concentration is determined from the magnitude of the current.

Composite materials based on reduced graphene oxide and polyaniline. Composition, morphology, electrochemical properties

It is shown that electrochemical characteristics of electrochemically synthesized composite materials (CMs) based on reduced graphene oxide nanosheets (RGONS) and polyaniline (PAni) depend considerably on the composition of CMs. Drastic variation of specific electrochemical capacity Cs in CMs is observed in the range of PAni content of 30–75 wt %. In the same range of compositions, practically full RGONS surface coverage by the synthesized PAni is observed, as shown by SEM.

Controlled electrosynthesis of polyaniline on branched surface of reduced graphene oxide

Electrochemical synthesis is used to obtained a number of composite materials (CMs) consisting of different layers of reduced graphene oxide nanosheets (RGONS) and polyaniline (PAni) coatings of different thickness synthesized on these layers. Ranges of PAni–RGONS weight content, at which the maximum values of capacity are reached, are determined. CM samples with high C values demonstrated higher stability in the course of electrochemical studies.

Electrochemical synthesis and study of poly(2,5-diarylamino-3,6-dichlorobenzoquinone) and its composite with multiwalled carbon nanotubes

A procedure has been developed for electrochemical polymerization of dianiline dichlorobenzoquinone and electrosynthesis of a composite material based on poly(dianiline dichlorobenzoquinone) and multiwalled carbon nanotubes (MCNTs) in 1 M H2SO4. The introduction of a polymerization initiator (potassium hexachloroiridate IrCl62− (HCI)) accelerated the growth of the electrode coating. The introduction of MCNTs led to the creation of a current-conducting framework in the composite and an increase in the mass and electrochemical capacity of the electrode coating. The electrochemical behavior of the composite is similar to that of polyaniline (PAni), but includes the redox reaction of the chloranil substituents. The charging of the double electric layer makes a significant contribution to the electrochemical capacity.