Nanocomposites and nanomaterials

Photocatalytic properties of the heterostructures based on TiO2 and TiO2-CdTe with a polymethine dye
Kobasa I.M.1, Kondratchuk I.V.1, Sema O.V.1, Panimarchuk О.І.2
1 Yu. Fedkovych National University of Chernivtsi.
2 Kotsyubynsky St., Chernivtsi, 58012, Ukraine.
E-mail: I.Kobasa@chnu.edu.ua
2 Bucovina State Medical University,
2 Theatralna Sq., Chernivtsi, 58002, Ukraine.

A problem related to development of highly effective and competitive photo- and catalytic systems has been remaining topical throughout many years because these solutions can be applied to many fields such as light and solar energy conversion, non-traditional low-cost synthesis technologies, decontamination of toxic wastes, deposition of metals on the dielectric substrates and others. As seen from the result of previous investigations, the heterostructures (HS) containing a semiconductor and the dye-sensitizer can be quite effective solution in this field. 
A representative of the steryl dyes, (1-phenyl-5,6-benzoquinoline-2)-2,4-dihydrosteryliodide was used as the dye component of the heterostructures while their semiconducting part was made of the Degussa TiO2 P25 or the p-type CdTe obtained by Bridgeman method. 
An influence of the dye nature on its spectral, electrochemical and energy characteristics has been investigated while its reduction and oxidation potentials were measured by the cyclic voltammetry. Then these potential values were used to calculate the dye HOMO and LUMO energies to evaluate a possibility of its utilization as a sensitizer for TiO2 and CdTe. A series of new light sensitive heterostructures based on TiO2 and cadmium telluride has been synthesized and their photocatalytic activity was measured in the test reaction of reduction of methylene blue by formaldehyde at various dye concentrations and irradiation modes. All obtained experimental results were discussed and explained.