Photocatalysis by ZnS nanoparticles of the formation of ZnS/Au heterostructure in the reduction of complex ions of gold

The photocatalytic activity of ZnS nanoparticles during the reduction of the KAu(CN)₂ complex was found. The spectral characteristics of the nanocomposite ZnS/Au⁰ and also the principal kinetic relationships involved in its formation were studied. It was shown that the photoreaction has equilibrium character resulting from oxidation of the obtained gold by holes in the valence band of the zinc sulfide. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 41, No. 6, pp. 343–347, November–December, 2005.     

Photocatalytic formation of porous CdS/ZnO nanospheres and CdS nanotubes

It was found that ZnO nanocrystals have photocatalytic activity in the formation of CdS during the reduction of sulfur in the presence of cadmium acetate. It was shown that mesoporous spheres measuring 150–170 nm and consisting of CdS/ZnO particles measuring 5–8 nm are formed during the irradiation of ZnO particles measuring 5.5 nm. During the photodeposition of CdS by the action of light on nanorods produced by ultrasonic treatment of microcrystalline zinc oxide nanotubes of CdS 0.5–0.8 μm in length and 15–110 nm in internal diameter are formed. A mechanism, in which they appear at the ends of the ZnO nanorods and grow on the surface of the CdS/ZnO heterojunction, is proposed for the formation of the CdS nanotubes. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 4, pp. 215–219, July–August, 2007.     

Mechanism of reactions of photocatalytic synthesis of chlorohydrins

A mechanism of photocatalytic synthesis of chlorohydrins from olefins and peroxo complexes of titanium (IV) is proposed. It consists of formation of radical-containing complexes, their reactions with olefins, and decomposition of the α-oxides obtained by hydrogen chlorides. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prosp. Nauki, 252039 Kiev, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 1, pp. 17–21, January–February, 1997.     

Photochemical Synthesis,Spectral-Optical and Electrophysical Properties of Composite Nanoparticles of ZnO/Ag

The photochemical synthesis of nanoparticles of ZnO/Ag in isopropanol solutions has been carried out. Their optical properties have been studied and the parameters of the plasma resonance of the nanoparticles of silver in the ZnO/Ag composites have been calculated. It has been established that the hypsochromic shift of the plasma band of silver observed on irradiation of the nanocomposite is a result of accumulation of excess electrons on the ZnO/Ag particles which leads to equalization of the potentials of the conductions zones of the semiconductor and the metallic components of the nanocomposite.     

Homogeneous photocatalysis of ethanol reduction of nitrobenzene by titanium complexes

It was shown that when ethanol solutions of nitrobenzene are irradiated with near-UV light, which is absorbed by labile complexes of titanium(IV) present in the system, aniline is accumulated. The quantum yield of C₆H₅NH₂ formation if weakly dependent on the C₆H₅N0₂ concentration and increases with increasing titanium(lV) content in solution.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, Nos. 5–6, pp. 416–419, September–December, 1992.     

Nanosecond and microsecond decay of photogenerated charges in Cd<Subscript>x</Subscript>Zn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>S nanoparticles

The luminescent characteristics of Cd_xZn_1−xS nanoparticles were studied. It was shown that the emission is due to the recombination of holes in the valence band with electrons captured by two sorts of traps, of which the traps with lower energy were ascribed to the surface states of the Cd_xZn_1−xS nanoparticles. It was established that the Cd_xZn_1−xS nanoparticles have more pronounced ability than CdS nanoparticles to accumulate excess negative charge under the conditions of pulsed irradiation. It was shown that the consumption of the photogenerated electrons in nanosecond and microsecond time scales involves the participation of one and the same electron traps. It was established that the rate of interaction of the electrons captured by the surface traps with oxygen increases with decrease in the size of the nanoparticles. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 5, pp. 275–281, September–October, 2007.     

Structure and spectral-optical characteristics of Se,Se/CdS,and Se/Cd<Subscript>0.5</Subscript>Zn<Subscript>0.5</Subscript>S nanoparticles,stabilized in polymer-containing media

A method was proposed for the production of colloidal nanoparticles of selenium stabilized by polymers and surfactants, and their structural and optical characteristics were studied. It was shown that during the deposition of CdS and Cd_0.5Zn_0.5S on the surface of the Se nanoparticles followed by dissolution of the selenium with sodium sulfite it is possible to obtain network “nanoframeworks” with size 30–50 nm, formed by CdS or Cd_0.5Zn_0.5S particles measuring 3–5 nm. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 1, pp. 24–29, January–February, 2007.     

Photochemical formation of semiconducting nanostructures

Existing data on photochemical and photocatalytic approaches to the formation of semiconducting nanoparticles and also binary semiconducting nanostructures and nanocomposites of semiconductors with metals and polymers are reviewed. The nature of the effect of irradiation on the synthesis and properties of the obtained nanostructures and the possibility of photocatalytic control of the structural and spectral parameters of nanostructural semiconducting systems are examined. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 4, pp. 199–220, July–August, 2008.     

Photocatalysis of the Reduction of Cd2+ Ions by CdS Nanoparticles in Isopropyl Alcohol

The kinetic relationships governing the photocatalytic reduction of Cd²⁺ cations with participation of CdS nanoparticles in isopropyl alcohol solutions were investigated. Quantum-dimensional effects that manifest themselves in an increase in the rate of the process with decrease in the average size of the photocatalyst nanoparticles were observed and interpreted. In the light of published data a scheme that agrees satisfactorily with the experimental results is proposed for the mechanism of the photocatalytic reduction of cadmium ions.     

Features of formation of CdSe nanoparticles in aqueous sodium polyphosphate solutions

A study was carried out on the features of formation of stable aqueous colloidal solutions containing CdSe nanoparticles stabilized by sodium polyphosphate resulting from a reaction between cadmium chloride and sodium selenosulfate. The major parameters determining the size of the CdSe nanoparticles are the reaction medium temperature and the ratio of the starting reagent concentrations. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 2, pp. 102–106, March–April, 2006.