A. A. Yavich

Synthesis and proton conductivity of adsorption-saturated and solvated porous hydroxyethylated cyclam layers on the surface of PVC-coated cellulose fabric

Porous layers of associates of adsorption-saturated and benzene- and hexane-solvated chloride and sulfate of hydroxyethylated cyclams with acid aqua complexes were synthesized on the surface of PVC-coated cellulose fabric. The porous structure of the layers includes a system of internal pores connected with the external pores via the diamine rings of the common walls of the hydroxyethylated cyclam nets; the internal pores are filled with the associates; the solvent molecules are adsorbed on the developed surface of the layers or solvate it. The H+ motion rate in a layer placed in solvent vapors or liquid solvents was measured; the layers were found to be nonlinear H+ conductors. The potential of H+ transition from the acid solution into the layer, the H+ mobility constant, and the field variation constant of the H+ mobility of the layer depend on the layer composition. The adsorption and solvation are accompanied by the formation of host-guest molecular complexes between the diamine rings of the cyclam nets and the benzene or hexane molecules, affecting the resistance of the associates to the incorporation of H+ ions and the H+ mobility in the associates.

Ion-conducting porous layers of sodium hydroxide complexes with hydroxyethylated cyclams on modified surfaces of a PVC coating for fabrics

Layers of polynuclear NaOH complexes with aza-crown groups are synthesized using a NaOH solution on porous layers with internal voids of macromolecular hydroxyethylated cyclams on a chemically modified PVC coating that encapsulates the fibers of a cellulose fabric. The porous structure of the layers is studied along with the adsorption of solvent vapors (benzene, hexane) and liquid solvents. The OH− conductivity of layers that act as electrochemical bridges is examined in air and the vapor and liquid phases of the solvent. It is established that the complexes occupy the voids and have a developed system of hydrogen bonds. The pores are filled during adsorption. Molecules of the solvent are connected by the macrocyclic groups of pore walls into a host-guest complex as the structural system of hydrogen bonds changes. It is observed that the motions of OH− ions start at a certain value of potential Eover. An expression describing the dependence of velocity of voltage is obtained: v′ = K1(E − Eover) + K2(E − Eover)2, where K1 is the conductivity constant of a layer and K2 is the constant of transfer acceleration, determined by the structural changes in the layer in a field of moving OH− ions. It is shown that the values of Eover, K1, and K2 depend on the composition of the complex and the nature of solvents.

Electrically conductive PVC layers filled with active carbon containing H+-conducting porous structures of sulfuric acid complexes of cyclams on fabrics

Electrically conductive PVC layers are synthesized. The layers are filled with active carbons containing porous H+-conductive structures of hydroxyethylcyclam/sulfuric acid complexes crosslinked with cellulose fabric. They are interlaid with layers based on the same structures containing added benzene and hexane adsorbates and solvates. It is found that upon anode or cathode polarization of the layers as H+-conductive electrochemical bridges in air and in the vapor and liquid phases of benzene and hexane, either the electroreduction of H+ to H2 or the electrooxidation of H2O to O2 occurs in the areas of contact between active carbon particles and the complexes. The dependences of rates of H2 and O2 formation on the voltage are studied. The magnitudes of overvoltage and the constants of electrochemical reactions are found to depend on the composition of a layer.

New nonplatinum electrocatalysts based on Ru for the direct oxidation of ethanol in an alkaline fuel cell

Anodic catalysts of the RuM type (RuNi, RuNiPd, RuCr, and RuV) for the oxidation of ethanol in an alkaline electrolyte were synthesized and studied. The activity of the catalysts increased in the series RuNi < RuCr < RuV and as the specific surface area of the carbon carrier grew. The RuV catalyst was found to be most active and stable because of its structural features, namely, the formation of the RuV solid solution decorated with oxides.

Materials based on carbon-filled porous layers of PVC cyclam derivatives cross-linked with the surfaces of asbestos fabric fibers

The synthesis of bilayer materials with porous upper layers composed of PVC hydroxyethylcyclam derivatives filled with carbon and a layer consisting of hydroxyethylcyclam, cross-linked via Si–O–C groups with the silica chains of a developed surface of asbestos fabric, is described. The aza-crown groups in these materials are bound with aqua complexes of H2SO4 or NaOH. The structure of the materials is examined, their adsorption characteristics are determined, and the rate of motion of H+ or OH– ions in electrochemical bridges is measured, while the formation of H2 and O2 in their cathodic and anodic polarization is determined as a function of voltage. It is shown that the upper layer of these materials is adsorption-active and electronand H+- or OH–- conductive, while the bottom layer is only H+- or OH–- conductive; through it, the upper layer is supplied with the H+ or OH– ions needed for the regeneration of the aqua complexes broken down to H2 and O2 on carbon particles.

Layers of cyclam-substituted PVC with sodium hydroxide aqua complexes with aza-crown ligands on cellulose tissue filled with active coal

A material with an electrically ОН–-conductive porous layer of cyclam-substituted PVC filled with active coal containing NaOH aqua complexes with aza-crown ligands and cross-linked with the surface of cellulose tissue fibers has been synthesized. The structure of the material was studied. Its sorption capacity in vapors and liquid benzene and hexane, specific resistance, potential of ОН- transfer from solution to layer, and rate constants of ОН– travel in the layer of the material as an electrochemical bridge in vapors and liquid benzene and hexane were determined. The aqua complexes decomposed in the layer with formation of Н2 during the cathodic polarization of the bridge and О2 during the anodic polarization; the composition of the complexes was regenerated due to the motion of ОН–.

Porous Proton- and Chloride-Ion Conducting Layers Based on Ethanolamine Derivatives of PVC on the Surfaces of Fabrics

Materials are produced with porous layers based on ethanolamine derivatives of PVC or compounds of active carbon with hydroxyethylcyclam derivatives of PVC with aqua complexes of chloride hydrogen cross-linked with the surface of cellulose or asbestos fabric. Their capacity for sorption with respect to hexane and benzene in the saturated vapor and liquid phases is determined. The dependences of current on voltage in a circuit are determined for bridges composed of these materials in air, and in the vapor and liquid phases of benzene and hexane between 3 M HCl solutions and 3 M HCl solutions containing 3 M CaCl2. It is established that only H+ ions migrate along the bridges between the HCl solutions, and H+ and Cl– ions were the only species that moved along the bridges between the HCl solutions containing CaCl2. The voltages at which the movement of ions starts are determined, and constants characterizing the conductivity of the layers are found. It is shown that these parameters depend on the structure of a layer, the nature of the fabric, and the medium surrounding a bridge.

Electrosynthesis of ammonia in hydrogen-producing sorption-active electrochemical matrix

A fundamentally new low-temperature method of synthesizing ammonia has been suggested, which is carried out directly in a hydrogen-producing matrix with a material made of cellulose fabric with porous layers of ethanol–cyclam PVC derivatives with activated carbon with aquacomplexes of sodium hydroxide grafted onto its fibers. Complexes of zero-valent nickel and iron within the cyclam structure are formed in the matrix. Hydrogen is formed on the cathode in the course of electrolysis of water from sodium hydroxide aqua complexes on particles of activated carbon as microelectrodes. Hydrogen forms bonds with complexes of zero-valent nickel. Nitrogen from adsorbed air is bound in complexes of zero-valent iron and interacts with active atomic hydrogen. Water is transported to carbon particles through the fabric onto which the layer is grafted. The process is carried out at the room temperature. It has been found that the forming hydrogen is almost completely used. As opposed to the existing methods of synthesis of ammonia, the suggested process is carried out at room temperature and normal pressure.

Electrochemically reactive matrices based on electron-ion conducting and adsorption-active tissues

A review of methods for the synthesis of new composite materials—electroactive and adsorption-active tissues, their electrochemical properties, and potential applications is presented. These are cellulose or asbestos fibers with porous layers linked to their surface, which consist of cyclam derivatives of PVC filled with active carbon, providing electric conductivity. The H+ or OH– ion conductivity is provided by the H2SO4 or NaOH aqua complexes with aza-crown groups in the pore walls. The high rate of ion transport was demonstrated in air, hexane, benzene, and their vapors. When the current is passed, H2 or O2 is evoluted, or redox transformations of the adsorbed substances occur on the carbon particles. The dependence of the characteristics of the material on its composition and adsorption equilibrium conditions was analyzed. The mechanism of its functioning was suggested. The material was shown to be promising for use in the production of H2 or O2 and acid–base or redox transformations of substances adsorbed from gaseous media or nonaqueous solutions.

Sorbents based on asbestos with a layer of an hydroxyethylcyclam derivative of PVC containing aquacomplexes of sulfuric acid or sodium hydroxide with aza-crown groups

Aquacomplexes of sulfuric acid and sodium hydroxide with aza-crown groups are synthesized in cavities of a sorbent from the porous layer of a PVC cyclam-derivative grafted onto fibers of asbestos fabric. The structure of sorbents with complexes is studied and their adsorption characteristics are determined. It is shown that the affinity of the developed surface toward ethanol, benzene, and hexane depends on the nature of complexes in the pore walls, and the volume of cavities formed as a result of the pores on the developed asbestos surface being coated with networks of aza-crown groups is larger than that of cavities with walls of aza-crown groups in the layers of a PVC cyclam derivative. Indicators of H+- and OH–-conductivity of sorbents with complexes as electrochemical bridges are determined. It is shown that the major part of H+- and OH–-ions moves through complexes with aza-crown groups in the region of cavities formed of pores on the surface of asbestos.