Том 53, № 12 (2017)

The specific electric conductivities (ECs) of concentrated aqueous solutions of electrolytes were shown to be comparable to the limiting high-frequency (HF) EC of water. The limiting HF EC of water is determined by the ratio of the absolute dielectric constant to the dipole dielectric relaxation time. It was assumed that the specific EC of an aqueous solution cannot exceed the limiting HF EC of water. The specific ECs of the 1.0 М aqueous solutions of lithium, sodium, and potassium chlorides were calculated from the limiting HF EC of water. At elevated temperatures, the specific ECs of aqueous salts were shown to increase in direct proportion to the limiting HF EC of water.

CaV_0.5Mo_{0.5 – x}Ti_xO_{3 – δ} samples with the perovskite structure were studied as a promising anode material for fuel cells with electrolyte based on substituted lanthanum gallate La_0.88Sr_0.12Ga_0.82Mg_0.18O_2.85 (LSGM). According to X-ray diffraction data, the solid-solution homogeneity region lies from х = 0 to х = 0.25. It is shown that CaV_0.5Mo_0.25Ti_0.25O_{3 – δ} is compatible with the LSGM-based electrolytes as regards both its chemistry and the coefficient of thermal expansion. Substitution of titanium leads to a decrease in the total conductivity but extends the p(O₂) range of phase stability of this material. It is demonstrated that in its composite with LSGM this material becomes more resistant to oxidation.

The electrochemical modification of activated carbons (AC) by a conducting polymer polypyrrole (PPy) has a substantial effect on the AC structure characteristics, electrochemical properties, and adsorption activity with respect to natural substances (by the example of free hemoglobin). Using the method of standard contact porosimetry (SCP), the porous structure and hydrophilic–hydrophobic properties are studied for the activated carbon SKT-6A, the [SKT-6A/PPy/Cl^–] composite, and individual polypyrrole. The chemistry of the activated carbon surface is studied by the standardized Boehm method. It is shown that the nature of activated carbon and its initial surface substantially affect the character of its interaction with the conducting polymer polypyrrole. The effect of such modification on the AC surface chemistry should be considered in aggregate by taking into account each component of such modification. The increase in the sorption ability of [AC/PPy/Cl^–] composites with respect to hemoglobin is largely associated with the stronger hydrophilicity of polypyrrole as compared with activated carbons.

The formation of the composite of reduced graphene oxide (RGO) with poly-o-phenylenediamine (PPD) on the surface of SnO₂-coated conducting glasses (CG) is studied by the methods of voltammetry, atomic force microscopy (AFM), electron microscopy (SEM) with energy-dispersive X-ray spectroscopic (EDXS) microanalysis, and electron spectroscopy, When a CG with deposited graphene oxide is placed into aqueous solution of o-phenylenediamine (OPD), the monomer is strongly fixed in the GO matrix, as confirmed by EDXS data. The further redox interaction in the two-phase system GO–OPD initiates polymerization of OPD in the GO film. When anodic polarization in switched on, the oxidation and the further polymerization of OPD go on, while GO is reduced to RGO as a result of mediated reaction to yield the RGO–PPD composite even in the absence of cathodic polarization. The electron spectra of composites reveal the presence of an absorption band close to absorption of individual PPD. According to AFM and SEM data, OPD incorporated into the composite structure keeps RGO from being folded in acidic media. As the time of impregnation increases, the degree of reduction of GO to RGO changes, which is reflected in the surface morphology and the amount of monomer in the composite (RGO–PPD)-1. The coating becomes black, which is typical of RGO, and its conductivity increases by 4–5 orders of magnitude.

Title of the paper should be:

Generalized Nernst Layer Model for Convective-Diffusion Transport. Numerical Solution for Bromate Ion Electroreduction on Inactive Rotating Disk Electrode under Steady State Conditions