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Vol 59, No 2 (2023)
Articles
The Electrophoretic Deposition of Lithium Cobaltate Nanosized Particles on the Surface of Metals and Electroconductive Oxide Ceramics
Abstract
The deposition of LiCoO2 nanosized particles synthesized in LiCl–CoCl2 melts on the surface of nickel foil, copper, chrome–cobalt alloy, and platinum mesh in aqueous solutions of lithium chloride at the room temperature as well as on the surface of the electron-conducting La0.6Sr0.4MnO3 oxide ceramics in chloride melt at temperature of ca. 700°C is studied. The methods of vibrational spectroscopy, X-ray photoelectron spectroscopy, ellipsometry, and scanning electron microscopy have revealed the features of the chemical composition, structure, and morphology of the precipitates obtained.
81-91
Comparative Study of Biocatalytic Oxidation of Some Organic Substrates Using Shewanella xiamenensis and Escherichia coli Microorganisms on Mediator and Non-Mediator Bioanodes
Abstract
In the work, a comparative assessment of the effectiveness of Shewanella xiamenensis and Escherichia coli microorganisms used as a biocatalyst in the process of bioelectrochemical oxidation of various substrates in neutral media on mediator-free and mediator bioanodes was carried out. It was shown that the rate of bioelectrochemical oxidation of the studied organic substrates (citric acid, glucose, sucrose) with the help of S. xiamenensis cells does not depend on the concentration of the mediator introduced into the system (methylene blue)—electron transfer from cells to the electrode occurs as a result of direct contact of cells with the electrode’s surface. A comparative kinetic analysis showed that S. xiamenensis cells are a less effective biological catalyst for the process of glucose oxidation compared to the E. coli microorganism (in the presence of a mediator). The kinetic characteristics of the glucose oxidation reaction in the “mediator–substrate–E. coli cells” system were determined. It was found that the order of the oxidation reaction with respect to glucose at the anode is equal to one, the rate constant of this reaction is 0.0214 min–1, and the half-life of glucose is 33 min. It is shown that the model system under study makes it possible to lower the concentration of glucose in the working solution to the value of the background current, which indicates an almost complete purification of the solution from the organic substrate. It is shown that in solving practical problems in order to increase the efficiency of wastewater treatment from organic substances using mediator-free bioanodes, it is necessary to search for new cells, including other cells of the Shewanella genus, with mandatory immobilization of cells on the electrode surface in order to increase electrical contact.
92-100
Effect of Current Density on Specific Characteristics of Negative Electrodes for Lithium-Ion Batteries Based on Heat-Treated Petroleum Coke
Abstract
The results of comparative studies of the effect of current density on the average discharge voltage and specific discharge capacity of carbon electrodes based on heat-treated petroleum coke and graphite are presented. The carbon obtained by heat treatment of petroleum coke is shown to have better kinetic characteristics than graphite. The increase in the current density from 0.2 mA/cm2 (36 mA/g) to 2 mA/cm2 (364 mA/g) leads to a decrease in the discharge capacity of heat-treated petroleum coke by 26%; graphite, by 93%. When the current density is restored to 0.2 mA/cm2, the discharge capacity of carbon electrodes is also restored to its initial value. The increase in the current density is also shown to lead to increase in the average discharge voltage of lithium–carbon cells. Thus, with the increase in current density from 0.2 to 2 mA/cm2, the average discharge voltage of the lithium–carbon cells with the electrode active component of the heat-treated petroleum coke increased from 0.39 to 0.62 V; that of graphite, from 0.14 to 0.35 V.
101-110
Effect of Ga3+ and In3+ Ions on the Anodic Dissolution of Aluminum in KOH Ethanol Solutions
Abstract
The anodic dissolution of aluminum in the KOH ethanol solutions is considered. It is shown that an addition of gallium and indium compounds to the 2 M KOH solution in 96% ethanol leads to an abrupt increase in the anodic dissolution current of aluminum near the open-circuit potential and its shift by 300 mV toward negative values. The discharge galvanostatic curves in the solutions with the additives of gallium and indium compounds contain a flat discharge plateau at the current densities up to 4 mA/cm2. The hydrogen evolution rate in a number of KOH ethanol solutions is measured.
111-116