Hybrid nanoparticles based on sulfides, oxides, and carbides

Abstract

The methods for synthesis of hybrid nanoparticles based on sulfides, oxides, and carbides of heavy and transition metals were considered. The problem of the influence of the method of synthesis of the hybrid nanoparticles on their atomic structure, morphology of the nanomaterials, and functional properties was analyzed. The areas of practical use of the hybrid nanoparticles were proposed.Key words: nanoparticles, sulfides, oxides, carbides.Special attention is given nowadays to the synthesis and application of nanostructured materials (nanomateri als) based on chemical compounds. 1-3 This is due to the changed properties of nanomaterials compared to those of materials with the same chemical composition but with magnified scale of structural elements. 4-20 The changes in the properties and the appearance of unusual combina tions of properties of the nanomaterials are related to the fact that the physical properties of chemical compounds are formed at distances from several nanometers to several tens of nanometers because of the characteristic nano sized radius of quasi particles (excitons, phonons, mag nons, and polarons). Therefore, a nanoparticle should have optical, electrical, magnetic, mechanical, and other prop erties differed from the properties of particles with the size 100 nm.Indeed, this behavior is observed, for example, for semi conductors with weakly bound excitons. The Bohr radius of exciton in these semiconductors considerably exceeds the atomic size and is equal to several nanometers. As a result, due to a decrease in the particle size of the semi conductor to several nanometers, a confinement of exci tons can be achieved and quantum dots (QDs) can be obtained. The semiconducting properties of QDs differ from those for large nanoparticles and materials. At ambi ent temperature, it is difficult to observe lines related to exciton states in the luminescence spectra of bulky semi conductors. The quantum yield from these states is low because of high values of effective radii of exciton. In ad dition, at ambient temperature excitons actively decom pose because of thermal motion. The energy of an exciton * Dedicated to the Academician of the Russian Academy of Sciences I. P. Beletskaya on the occasion of her anniversary.

Size and zeta potential of CdS nanoparticles in stable aqueous solution of EDTA and NaCl

“…At present, the synthesis of hybrid nanoparticles based on semiconducting sulfides possessing photo catalytic properties is of great practical interest for both basic research and practical application [4][5][6][7][8][9][10]. Most techniques for producing quantum dots use toxic precursors, which limits their utility in biological and medical applications, so additional steps are needed to transfer quantum dots to aqueous solutions compati ble with biological objects [2,3,9].…”

Synthesis of nanocrystalline silver sulfide

“…In addition to the development of methods for the preparation of semiconductor nanoparticles, consid erable research effort has been concentrated on the possibility of producing nanoparticles of controlled size and shape [1,2].…”

Nonstoichiometric titanium dioxide nanotubes with enhanced catalytical activity under visible light

“…Nanostructural modifications of titanium dioxide are of great research interest, particularly in the development of promising functional media for renewable energy sources (i.e., solar cells and the photochemical decomposition of water) [1][2][3][4] , selective organic synthesis with atomic precision for direct C-H functionalization of a variety of organic molecules 5 , the manufacture of efficient photoelectric transducers and memristor memory cells 6 , the development of photocatalysts for the removal of organic impurities [7][8][9] , and other applications [10][11][12] . The optical gap width of stoichiometric TiO 2 (>3.1 eV) determines its photocatalytic activity under the action of near -UV radiation, which constitutes only a small percent of the solar spectrum 13 .…”