Nanocomposites and nanomaterials

The kinetic model of nanoscaled metal formation on the surface of different forms of graphite 

Matzui L. Yu., Vovchenko L. L., Ovsienko I. V., Tsaregradskaya T. L.,  Saenko G. V.,  Marinin O. D.

1 Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Street, 
City of Kyiv, 01601 Ukraine
E-mail: marininoleg907@gmail.com

The physicochemical model of the process of the oxide phase formation on the surface of graphite materials has been developed. In the framework of the model, the essence of which consists in the heterogeneous formation of a metal oxide phase at the border of graphite salt, the average particle size of oxide formed on the surface of graphite as a result of salt thermolysis was estimated. This size was shown to be determined by three factors: the topology of graphite material surface, the properties of salt and the thermodynamic parameters of thermolysis reaction. It was shown that the most important factor determining salt thermolysis and characteristics of the final products is the temperature of reaction. 
The comparative analysis of the structure and phase composition of graphite-metal nanocomposites prepared under different temperature-temporal conditions showed the thermolysis decomposition of salt on the surface of graphite supporter is a complex multistage process. The duration of each stage and characteristics of final product are determined by the simultaneous action of series of factors: the type of graphite material, the state of its surface, the type of salt and the thermodynamic kinetic conditions of reactions. The desirable size, homogeneity and uniformity of distribution of the final product could be obtained by the variation of these parameters. 
The kinetic model of nanoscaled metal formation on the surface of different forms of graphite based on the unified description of all stages of metal component formation (salt crystallization, salt thermolysis on the surface of graphite supporter and oxides reduction) has been proposed. A system of equations was obtained, which allows one to describe the kinetics of each stage and the process of obtaining the metal graphite composite by recovering the metal from the water-salt solution. The developed unified generalized model of processes that take place during the formation of a nanoscale metal phase on the surface of a graphite carrier allows us to describe each stage of these processes for various types of graphite materials and salts, as well as the modes of implementation of each stage.