Influence of the melt composition on the cathode current density in electrode reactions
Within the framework of the Dogonadze-Kuznetsov-Levich theory, using the model of isotropic spherically symmetric bands with a root dependence on the energy of density of states, an expression for discharge currents at the dielectric/electrolyte interfacial boundary was obtained. An approach to estimate average density of electronic levels from which heterogeneous charge transfer takes place is proposed. An expression for obtaining a numerical value of cathode current density was established. Conditions of surface conductivity occurrence of a dielectric in a saline melt without its prior metallization are formulated. It is substantiated that the type of surface conductivity depends on reorganization energy, energy of reactants and reaction products in electrode field, transmission coefficient and other values which are determined by chemical composition of electrolyte, and can be calculated by analytical or quantum chemical methods. It was established that the adsorption of carbon dioxide on the surface of dielectric leads to a significant polarization of surface towards conduction band. The width of the band gap decreases, but the dielectric character of the cluster does not change, there is no band overlapping, i.e. an electrode does not acquire semiconducting and semimetallic character of conductivity. At the same time, adsorption of ВO2– on electrode surface leads to a strong polarization of the surface cluster towards the valence band, whlist a the band gap width decreases slightly, less than in the case of carbon dioxide.
K. Liu, Z. Wang, Z. Yin, L. Cao, J. Yuan, Effect of Co content on microstructure and mechanical properties of ultrafine grained WC-Co cemented carbide sintered by spark plasma sintering, Ceram. Int. 44, 18711 (2018); https://doi.org/10.1016/j.ceramint.2018.07.100.
J. Garcia, V.C. Cipres, A. Blomqvist, B. Kaplan, Cemented carbide microstructures: a review, Int. J. Refract. Met. Hard Mater. 80, 40 (2019); https://doi.org/10.1016/j.ijrmhm.2018.12.004.
V.I. Shapoval. H.B. Kushkhov, V.V. Malyshev et al., Deposition of Molybdenum Carbide onto the Diamond Surface by Electrolysis of Ionic Melts, Powder metallurgy. 7, 43 (1986).
V.V. Solovyov, V.V. Malyshev, A.I. Gab, Physicochemical processes at the dielectric/oxide melt interface and their application in the electrocoating of diamond powders, Theoretical foundations of chemical technology. 38(2), 219 (2004).
R.R. Dogonadze, Yu.A. Chizmadzhev, Kinetics of some electrochemical redox reactions in semiconductors, Dokl. AN SSSR, 150(2), 333 (1963).
Firefly and PC GAMESS /Firefly version 8.0.1. Access mode. [Electronic resource]. Alex A. Granovsky. http://classic.chem.msu.su/gran/games/forum/discussion.html.
In memory of Alex A. Granovsky. [Electronic resource]. http://classic.chem.msu.su/gran/gamess/index.html.
S. Kovalenko, V. Soloviev, Kinetics of the Elementary Act of Electrochemical Reactions at the Semiconductor–Electrolyte Solution Interface, Zeitschrift fuer Naturforschung, A: Physical Sciences. 69a. 654. (2014); https://doi.org/10.5560/ZNA.2014-0063.
V.V. Malyshev, V.V. Soloviev, L.A. Chernenko, V.N. Rozhko, Management of composition cathodic products in the electrolysis of molybdenum-, tungsten- and carbon-bearing halogenide-oxide and oxide melts, Mat.–wiss. u. Werkstofftech, 46(1), 5 (2015); https://doi.org/10.1002/mawe.201400331.