Semiconductor-ruthenium complex systems

Other Semiconductor-Ruthenium Complex Systems. Taqui Khan et al. used a ruthenium(III)-EDTA-bipyridyl complex as a photosensitizer in a Pt-Ti02 semiconductor particulate system [109]. The Ti02 powder was loaded with platinum by the procedure of Erbs et al. [110]. Here 50 mg of the Pt-Ti02 powder was stirred in 10 mL of 0.001 M K[Ru(EDTA)(bipy)] 3 to deposit the ruthenium complex on the Ti02 surface. The 3-treated powder was separated by centrifugation and dried at room temperature. 

Kalyanasundaram K., Gratzel M. Applications of functionalized transition metal con5)lexes in photonic and optoelectronic devices. Coord. Chem. Rev. 1998 77 347-414 Kamat P.V. Photoelectrochemistry in particulate systems. 3. Phototransformations in the colloidal TiOa-thiocyanate system. Langmuir 1985 1 608-611 Kamat P.V., Bedja I., Hotchandani S., Patterson L.K. Photosensitization of nanocrystalline semiconductor films. Modulation of electron transfer between excited ruthenium complex and SnOa nanocrystalUne with an externally applied bias. J. Phys. Chem. 1996 100 4900-4908 Kamat P.V., Vinodgopal K. Environmental photochemistry with semiconductor nanoparticles. Mol. Supramol. Photochem. 1998 2 307-350... 

Ruthenium bipyridyl complexes are suitable photosensitizers because then-excited states have a long lifetime and the oxidized Ru(III) center has a longterm chemical stability. Therefore, Ru bipyridyl complexes have been studied intensively as photosensitizers for homogeneous photocatalytic reactions and dye-sensitization systems. The Ru bipyridyl complex, bis(2,2 -bipyridine)(2,2 -bipyri-dine-4, 4,-dicarboxylate)ruthenium(II), having carboxyl groups as anchors to the semiconductor surface was synthesized and single-crystal Ti02 photoelectrodes sensitized by this Ru complex were studied in 1979 and 1980 [5,6]. 

Dyes such as erythrosin B [172], eosin [173-177], rose bengal [178,179], rhodamines [180-185], cresyl violet [186-191], thionine [192], chlorophyll a and b [193-198], chlorophyllin [197,199], anthracene-9-carboxylate [200,201], perylene [202,203] 8-hydroxyquinoline [204], porphyrins [205], phthalocyanines [206,207], transition metal cyanides [208,209], Ru(bpy)32+ and its analogs [83,170,210-218], cyanines [169,219-226], squaraines [55,227-230], and phe-nylfluorone [231] which have high extinction coefficients in the visible, are often employed to extend the photoresponse of the semiconductor in photoelectro-chemical systems. Visible light sensitization of platinized Ti02 photocatalyst by surface-coated polymers derivatized with ruthenium tris(bipyridyl) complex has also been attempted [232,233]. Because the singlet excited state of these dyes is short lived it becomes essential to adsorb them on the semiconductor surface with... 

Nasr, C., Kamat, P. V. and Hotchandani, S. (1998). Photoelectrochemistry of composite semiconductor thin films. Photosensitization of the Sn02/Ti02 coupled system with a ruthenium polypyridyl complex. J. Phys. Chem. B 102(49), 10047-10056. 

Photocurrent generation is one of the most interesting direct applications of photosynthetic studies. The adsorption of sensitizers onto semiconductor surfaces has been found to be an efficient way to generate photocurrents and has been studied extensively. Ruthenium bipyridyl complexes, in particular, have been the focus of recent research [137-139]. In these cases, only the first layer of molecules, which is in direct contact with the surface, is active. A highly porous semiconductor material was therefore employed to compensate for the low level of absorption of the single molecular layer. Other varieties of chromophores, semiconductor materials, and electron carriers for totally solid systems have been the subjects of extensive studies. The present... 

The study of heterogeneous systems in which a donor or acceptor is linked to the surface of a conductor or semiconductor has been of considerable interest, especially when electron injection into the semiconductor or electrode can be induced by light absorption of the linked dye molecule. Such systems have potential for the transduction of solar radiation into electrical energy. Gratzel and co-workers have used a ruthenium(II) complex linked to Ti02 by means of a Aw-carboxylato-bipyridine ligand to construct a reasonably efficient photo-ceii 16.381-383,390,402 details of the functioning of this photocell are not well understood,... 

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