Vol 59, No 6 (2023)

This paper presents the results of a study of the catalytic activity of bimetallic materials synthesized based on Vulcan XC-72 carbon black modified with nickel, cobalt, and molybdenum in the electrochemical oxygen reduction reaction. The studies of the synthesized catalysts by adsorption–desorption of nitrogen in vacuum show that they are mesoporous and possess low porosity and surface area. After modification with metals, the surface area of the catalyst and pore volume decrease. The Raman spectra of the samples evidence probable formation of intermetallics or mixed molybdenum oxides on the surface of the MoCo/C and NiMo/C catalysts, which is in agreement with the published data. Scanning electron microscopy shows the formation of spherical metal parties on amorphous Vulcan XC-72. All the studied bimetallic catalysts possess similar kinetic characteristics of the electrochemical oxygen reduction reaction; nevertheless, NiMo/C and NiNi/C catalysts manifest a higher activity. The verification of the robustness of operation of the synthesized catalysts shows their high corrosion resistance.

Using gas chromatography, we studied the influence of the nature of substituents in the β-cyclodextrin (CD) molecule on the sorption properties and the possibility of complex formation with the macrocycle of 26 organic compounds (hydrocarbons and alcohols) in binary sorbents based on the smectic–nematic supramolecular liquid crystal 4-(3-hydroxypropyloxy)-4'-formylazobenzene (HPOFAB) and four derivatives β-CD. It has been established that the nature of the substituents in the β-CD molecule significantly affects the manifestation of solvation interactions between LC and macrocyclic additive and, as a consequence, the mesomorphic, sorption, and selective properties of the studied composite sorbents.

The purpose of this work was to study the composition of cluster ions in samples containing sodium stannate and tin(II) chloride. It has been shown that the composition of mass spectra is influenced by such parameters as the laser radiation energy and the substance content in the sample being studied. Conditions for preparing samples and recording mass spectra using these parameters were optimized. Presumptive identification of peaks in the recorded mass spectra was carried out. It has been shown that many of the ion peaks observed in the mass spectra may correspond to clusters containing tin. In the mass spectra of sodium stannate, ions of the general composition SnxOyNazHm were detected, in which the number of tin atoms reaches eight, and the maximum ion mass-to-charge ratio (m/z) is 1100. In the mass spectra of tin(II) chloride, there are ions of the general composition SnxOyHmClp and SnxCly, where the number of tin atoms reaches 4, and the highest m/z value is 1000.

Copper(II) diethyl mesoporphyrinate (CuMP), as well as luminescent materials based on it, namely, films of CuMP in polystyrene and microparticles of aluminum oxide covered by a layer of CuMP, is obtained. An analysis of the change in the photoluminescence spectra of the new materials in a range of temperatures of 77–298 K is conducted. It is found that, upon varying temperature in the photoluminescence spectra of CuMP in polystyrene, the ratio of the intensities of phosphorescence from the triplet electron levels 2T1 and 4T1 changes and a shift of the spectra according to the Stokes law is observed. A change in the ratio of the intensities of emission from the levels 2T1 and 4T1 is also observed in the luminescence spectra of CuMP adsorbed on the surface of microparticles of Al2O3 upon varying temperature; however, an anti-Stokes shift of phosphorescence from the level 2T1 is observed at the same time. An analysis of the kinetics of decay of the phosphorescence spectra of the CuMP dye in composite materials that possess the properties of luminescent temperature sensors is conducted.

Using voltammetry and chronoamperometry, the formation process and properties of insulating nanofilms of alkanethiols with different chain lengths (butane-, octane-, dodecanethiol) obtained on an oxide-free copper surface were studied. The electrochemical method for modifying the copper surface includes the removal of the oxide layer by its cathodic reduction, the adsorption of a thiol under electrochemical control, followed by studying the properties of the resulting nanofilm by voltammetry in one solution. It is shown that, with this approach, a dense thiol film is formed, with its blocking properties depending on the adsorption potential, the time of contact of the electrode with the thiol-containing solution, the thiol concentration, and the presence of dissolved oxygen in the solution. The introduction of ethanol into an aqueous alkali solution leads to a significant acceleration of the process of self-assembly of dodecanethiol, but greatly inhibits the process of self-assembly of butanethiol. The approach proposed in this work makes it possible to use aerated low-concentration thiol-containing solutions to obtain alkanethiol films on the Cu surface with good blocking properties.

Methods have been developed for preliminary modification of the surface of structural metals with compositions based on organosilanes, including both solutions of individual organosilanes and two-component mixtures consisting of two organosilanes or an organosilane with an organic corrosion inhibitor. As a result of this modification, self-organized siloxane polymer/oligomer nanosized layers are formed on the metal surface. Such layers are capable of changing the physical and chemical properties of the metal surface, in particular its electrochemical behavior. In this work, the influence of organosilicon surface layers on the electrochemical behavior of carbon steel, especially on the anodic local dissolution of the metal, is studied in detail. Inhibition of metal dissolution by surface layers has been shown. It has been established that the greatest inhibitory effect is exhibited by two-component modifying compositions, namely, mixtures of vinylsilane with aminosilane and vinylsilane with benzotriazole. The mechanism of corrosion inhibition by surface nanolayers formed during surface modification with two-component mixtures is considered.