The properties of TiO 2 /CdS nanohetero structures produced by the chemical and photocatalytic deposition of CdS nanoparticles on the surface of nanocrystalline films of TiO 2 under the conditions of laser pulse photolysis were studied. It was shown that in the case of photocatalytically formed TiO 2 /CdS nanocomposites the spatial separation of the photogenerated charges between the components of the hetero structure, leading to the formation of intermediates of the photochemical transformations (Ti III centers in the TiO 2 nanoparticles and S -× radical-anions in the CdS nanoparticles), is an order of magnitude more effective.In the arsenal of methods used today for the production of semiconducting (SC) nanostructures a special position is occupied by photochemical methods that make use of the tendency of the initial reagents to undergo transformations leading to the formation of semiconducting nanoparticles and the ability of the semiconducting materials to induce photocatalytic processes as a result of which binary semiconductors or metal-SC nanohetero structures are formed [1]. These methods make it possible to control freely the properties of the obtained products and in particular the size and the optical characteristics of the semiconducting nanoparticles and, in the case of semiconducting nanohetero structures, to obtain photocatalysts for redox transformations more active than those produced by traditional methods. Thus, we established [2] that TiO 2 /CdS, TiO 2 /PbS, and TiO 2 /Cu x S nanohetero structures are formed on the surface of nanocrystalline films of titanium dioxide during the photocatalytic reduction of sulfur by ethanol in the presence of Cd II , Pb II , or Cu II salts. It was shown on the basis of atomic-force microscopy that cadmium sulfide is deposited in the form of nanorods with lengths up to 70-80 nm normal to the surface of the TiO 2 film and consisting of individual CdS particles 5-6 nm in diameter. It was suggested that on account of their anisotropic 302 0040-5760/09/4505-0302

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We have used the sol-gel method to synthesize titanium dioxide in the pores of an anodic aluminum oxide membrane. The samples were used for the test reaction of degradation of the organic dye rhodamine B. The concentration of the dye rhodamine B was monitored from the change in the absorption spectra in the 554 nm region, for an aqueous solution containing the dye and exposed to the emission from a mercury lamp. The synthesized samples of titanium oxide xerogel in the porous anodic aluminum oxide membrane are efficient photocatalysts for decomposition of organic dyes in an aqueous medium.Introduction. From the time photocatalytic decomposition of water on TiO 2 electrodes was discovered in 1972, photocatalytic oxidation of aqueous and gaseous contaminants has been studied intensively with the aim of solving the problem of environmental pollution [1][2][3][4]. Compared with other semiconductors, TiO 2 has found broad application due to its physical and chemical stability, corrosion resistance, low cost, and lack of toxicity. The TiO 2 bandgap width is 3.2 eV and 3.0 eV for anatase and rutile respectively [5]. Practically any organic compound can be oxidized on the surface of TiO 2 down to CO 2 and H 2 O, so design of photocatalysts based on TiO 2 to remove toxic organic substances from water and air is an important and quite realistic applied problem. Recently studies of catalytic processes using TiO 2 have been aimed at obtaining immobilized catalysts in the form of thin films with an extended surface and stable porous structure, making it possible to reduce energy costs associated with separation of reaction mixtures when using powdered catalysts [6].Accordingly, interest in photocatalysis has been focused on development of methods for synthesis of porous titanium oxide, such as anodizing titanium and obtaining semiconductor TiO 2 nanotubes for oxidative photoelectrochemistry [7], using pore-formers [8] and templates to form a regular mesoporous structure [9]. Films have been deposited both on the smooth surface of glass, metal, and silicon and also on the smooth surface obtained by etching borosilicate glass in hydrofluoric acid [8].Alternatively, to us it seems feasible to form a porous titanium oxide by the sol-gel method, using the tubular surface of porous anodic aluminum oxide as the base [10][11][12][13][14].Experimental Procedure. Samples of aluminum foil (99.99% pure) of thickness 0.2 mm were degreased in a solution based on potassium dichromate (3%) and sulfuric acid (80%) and, after washing and drying, were electrochemically polished in a mixture of ethanol and perchloric acid (5:1) at T ≤ 15