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The behavior of novel electroactive material based on reduced graphene oxide (RGO), poly-o-phenylenediamine (PPD), and silicotungstic acid (SiW) is studied using the methods of cyclic voltammetry (CVA) and electrochemical impedance. It is found that graphene oxide (GO) has a catalytic effect on the electrochemical codeposition of PPD and SiW onto the GO film during fabricating the RGO–PPD–SiW composite. It is shown that the composite has at least six redox transitions depending on the chosen range of cycling potentials. It is found that, at the potentials of 200 and 500 mV (Ag/AgCl), the conductivity of the composite is by 4 orders of magnitude higher than that of PPD. By the example of quinone-hydroquinone and ferro-ferricyanide redox reactions, it is shown that, in this potential range, the composite exhibits electrocatalytic properties, though neither PPD nor SiW individually exhibit pronounced redox transitions in this potential range.

The methods of silicotungstic acid (SiW) immobilization on conducting substrates were studied. For SiW immobilization by codeposition, poly-o-phenylenediamine (PPD) redox polymer was used. The most effective codeposition of SiW and PPD was demonstrated on a graphene oxide (GO) film. Meanwhile, GO is reduced to form RGO-PPD-SiW electroactive composite. The structure of the novel material was evidenced by cyclic voltammetry and IR and Raman spectra. PPD-SiW and RGO-PPD-SiW composites were studied by impedance spectroscopy, where an equivalent circuit was proposed. Film resistance Rf was shown to decrease in the series of PPD → RGO-PPD → RGO-PPD-SiW. Further, RGO-PPD-SiW has better transfer properties (bulk film diffusion rate). This enabled suggesting that the composite has better electrocatalytic properties than PPD and RGO-PPD as was evidenced for example of [Fe(CN)6]4−/3− redox transfer on the electrode coated with the novel material.

The formation of a nanocomposite coating based on reduced graphene oxide (RGO) and poly(o-phenylenediamine) (PPD) in the chemical reaction of graphene oxide (GO) and o-phenylenediamine (OPD) has been studied by cyclic voltammetry (CVA), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). It has been shown that the action of cyclic polarization provides a more uniform structure of the nanocomposite films (decrease in the corrugation effect). In addition, it has been found that the polarization of GO films containing the OPD monomer distributed inside to the PPD synthesis potentials leads to the formation of uniformly distributed globular structures, which most probably correspond to a polymer electrochemically synthesized in the space between the GO nanosheets.

Formation of an electroactive composite based on graphene oxide and poly-o-phenylenediamine (PPD) was studied. Electron absorption spectra were used to confirm formation of a strong chemical bond at a prolonged contact of unreduced graphene oxide on a conducting support (glassy carbon, SnO2) and o-phenylenediamine monomer solution. Here, graphene oxide is partially reduced and oxidation and partial polymerization of o-phenylenediamine starts. It is shown that electrochemical oxidation of the obtained composite under the conditions of cyclic voltammetry results in the further polymerization of o-phenylenediamine bound to graphene oxide; here, reduction of graphene oxide continues, and at much lower cathodic potentials than in the absence of o-phenylenediamine. Morphology of the obtained composite was studied using the AFM technique. PPD embedded into the composite structure does not allow nanosheets of reduced graphene oxide (RGO) to corrugate and imparts the morphology of the composite the shape of globules with a clearly pronounced structure. As a result, the RGO–PPD composite was obtained that demonstrated pronounced electroactivity in a wider range of potentials than in the case of nonmodified PPD.

This study concerns a simple method for modifying graphene oxide (GO) and its poly-o-phenylene diamine composite with palladium microparticles. When the films of graphene oxide (GO) or composite thereof with poly-o-phenylenediamine (RGO-PPD) are immersed into a solution containing palladium ions, the latter were shown to fix within the films and can be further reduced to the metal state. The changes following penetration of Pd2+ into GO and RGO-PPD films were recorded by means of cyclic voltammetry, Raman spectroscopy, and XPS. UV spectra evidenced the loss of palladium ions in the solution after immersion of GO films therein. GO appeared a good basis for creating composites with pre-selected particles that can be further used for preparing materials with target properties.

Carbonized tissue (CT) was used for the first time to prepare developed surface coated with electroactive polymer. A stable monolayer of electroactive heteropolyacid was found to result from CT impregnation with silicododecamolybendic acid (SiMo) solution. Successful electrochemical oxidation of o-phenylenediamine (OPD) was first demonstrated both on pure carbonized tissue and on the tissue coated with SiMo monolayer, while the oxidation potential on both pure and impregnated CT is shifted by 0.6 V more cathode from the OPD oxidation potential on “smooth” electrodes. OPD oxidation was found to yield primarily water-soluble oligomers on pure CT and solid PPD layer on SiMo-modified tissue.

Accumulation of palladium ions in poly-o-phenylenediamine (PPD) redox polymeric matrix was studied by means of cyclic voltammetry (CVA), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and spectroelectrochemistry. CVA and XPS studies demonstrated nitrogen atoms binding palladium cations upon impregnation of PPD film with palladium chloride solution. Higher residual reduced or partially reduced PPD form of cathodic polymer doping was shown to increase the number of palladium cations in the polymeric matrix. AFM recorded a significant effect produced to the film surface structure by intercalation of both palladium cations and metal formed by reduction of cations.

A new method for chemical production of composites based on poly-o-phenylidenediamine (PPD) by oxidizing o-phenylidenediamine (OPD) with silicomolybdic acid (SiMo) in neutral and acidic media is developed. Electrochemical and spectroelectrochemical studies reveal the presence of small deviations in the properties of composites synthesized. Cyclic voltammetry studies show that the composites are active and exhibit sufficiently high electrochemical stability. The presence of SiMo anions in the PPD matrix is confirmed by electrochemical and spectral studies in combination with x-ray microanalysis of composites. The ratio between the number of phenylazine polymeric links and heteropolyanions is found.

Poly-o-phenylenediamine films applied to ITO are modified by rhenium oxides using cyclic voltammetry in an ammonium perrhenate sulfate solution. Electrochemical and spectroelectrochemical properties of the composite thus obtained are studied. It is shown that all its components undergo reversible redox conversion.

Application of both cyclic voltammetry and rotating disc electrode technique to the study of the mechanism and kinetics of dissolved redox-species reactions (such as Fe 2+/3+ , Fe(CN) 4−/3− 6 and ce 3+/4+ ) at a Au electrode coated with poly- o -phenylenediamine (PPD) are discussed. The results show that the half-wave potential values for the reduction of these species at polymer modified electrode are distributed near the standard (formal) potential of PPD. In this case the reactions occur at the polymer/solution interface. One extra wave is observed for negatively charged redox-species due to occurrence of the reaction at the metal/polymer interface under semi-infinite diffusion conditions. The difference between the mechanism of electrochemical reactions at electrodes coated with electronically conducting and conventional redox-polymer films is connected with the difference of the equilibrium potential distribution in these two systems.

The anodic synthesis of a poly-o-phenylenediamine film at gold, platinum, and ITO electrodes and peculiarities of its doping–undoping are studied by cyclic voltammetry. Absorption spectrum of undoped films is obtained in visible and near-IR light.