Thesis for a candidate’s degree in physics and mathematics according to the specialty 01.04.18 – «Physics and chemistry of the surface». – Chuiko Institute of Surface Chemistry, National Academy of Science of Ukraine, Kyiv, 2021.
A method of nanopowder synthesis using electric explosion of wires has been developed, in which EEW synthesis is combined in time with other syntheses and processes in order to use synthesized nanopowders as superactive precursors, which is a new tool for solving problems in nanotechnology. The end product is new types of nanomaterials: a new type of plasma nanocoatings for catalytic applications and a new type of nanofilms for the manufacture of sensor active elements, in which the nanodispersed structure is fully preserved and free of organic binders, carbides and hydroxides, chlorine and fluoro. The final product is also nanopowders synthesized in low-temperature reactions using EEW nanopowders as superactive precursors.
Implemented a technique of forming a directed electric explosion of nanodisperse coatings W/Cu with an interface layer of nanoalloy W-Cu.
In this work, X-ray photoelectron spectroscopy (XPS) was used as one of the main elements of the process of synthesis of EEW nanopowders. XPS was used to determine in real time the optimal energy regimes of electric explosion of wires through the control of charge states of the surface of nanopowders, which reflect the maximum degree of defect of their surface. The combination of EEW and XPS methods allowed for controlled synthesis and solving the problems of classical synthesis of nanopowders by the methods implemented in the dissertation.
For the first time a new type of plasma nanocoatings WO3-x/stainless steel was obtained for the manufacture of catalysts on metal strips. The nanodisperse structure is completely preserved in the coatings, their surface contains active centers in the form of metal ions with reduced oxidation state and oxygen vacancies.
The peculiarities of the electronic structure of the surface of TiO2, TiO2:Ag nanopowders and the binding energy of Ti2p- and Ag3d- levels under different annealing conditions have been established. In TiO2-x:Ag with increasing Ag content simultaneously increases the contribution of Ti3+- states. Doping with silver synthesized EEW of TiO2 nanopowders leads to an increase in the activity of TiO2-x:Ag in photo- and electrocatalysis. The values of the photoelectrochemical current and the potential of the flat zones E in electrocatalysis and the rate constants of the reduction reaction K in photocatalysis are proportional to the relative content of metallic silver and the relative content of Ti3+- and Ag1+ -, Ag2+ states on the TiO2:Ag surface. For the first time, a new type of mesoporous nanodisperse films from TiO2, TiO2-x:Ag nanopowders was obtained.
The peculiarities of the electronic structure of the surface of WS2 nanopowders, the presence of two surface nonstoichiometric phases and the binding energy of the W4f- and S2p- levels of the atoms of these phases have been established. The reaction temperature of WО3-х + 3H2S WS2 + S + 3H2O of WS2 synthesis was reduced from 800С to 450С using WO3-x nanopowders as superactive precursors.
At 600°C, TiC was synthesized on the surface of TiO2, the shell of the modified TiH2/TiO2/C micropowder. The peculiarities of the electronic structure of TiO2-x-TiC compounds, the binding energies of Ti2p-, C1s-, O1s- levels of atoms and the main stages of TiC synthesis during reductive annealing of TiO2/C in vacuum using TiH2 as a source of atomic hydrogen have been established by the XPS method.
It is proposed to use TiH2 as a source of atomic hydrogen in nanosystems of the «core/shell» type for local synthesis on the surface of nanoobjects in a vacuum or inert atmosphere.
Key words: electric explosion of wires, EEW, nanopowders, nanodisperse plasma coatings, nanodisperse films, XPS.
