The Influence of Nanosized Active Particles of the Melt and the Electrode Surface on Charge Transfer Processes at the Electrode/Melt Interface

By using methods of quantum chemistry, in order to study a mechanism of electrode processes at the electrode/melt interface, calculations of reorganization energy were made within a model of conductive ellipsoids, which generalizes the Marcus model for a case when reagents are substantially non-spheric. It was ascertained that a value of reorganization energy of a dissolvent hardly varies at all intervals of distances between an electrode surface and a reagent and decreases substantially with an increase in a reagent charge. The values of activation energy for charge transfer at the electrode/melt interface were calculated. A decrease in the values of activation energy for charge transfer between a cathode surface and particles of a melt was established. The values of molecular orbital energies were calculated for a fragment of an electrode surface and active complexes of model melts. Based on the analysis of activation energy values and values of energy of highest occupied and lowest unoccupied molecular orbitals of the interacting structures, a conclusion was made about the essential role of a cationic composition of an electrolyte in the processes of electroreduction at the cathode. The analysis of the obtained theoretical results allows us to formulate the conditions for the occurrence of surface conductivity of the dielectric in the salt melt. A presumption was made that a selection of an electrolyte composition allowed controlling the rate of redox reactions at the electrode/melt interface without prior metallization of the dielectric i.e., a targeted change in the cationic composition of a melt makes it possible to achieve concurrence of energy levels of the electrode surface and the active complex, thereby enabling control over the synthesis of nanoparticles at the cathode. It was established that the mechanism of electrode processes at the electrode/melt interface is based on a shift in the Fermi level of a cluster of a solid-state body surface as well as equality of energies of marginal molecular orbitals of a pre-reaction complex and a cluster, which are determining factors in heterogeneous redox reactions at the surface of a dielectric immersed in a corresponding ionic melt.