Electron-transfer reactions photoelectrochemical cells

Metal oxide electrodes have been coated with a monolayer of this same diaminosilane (Table 3, No. 5) by contacting the electrodes with a benzene solution of the silane at room temperature (30). Electroactive moieties attached to such silane-treated electrodes undergo electron-transfer reactions with the underlying metal oxide (31). Dye molecules attached to sdylated electrodes absorb light coincident with the absorption spectmm of the dye, which is a first step toward simple production of photoelectrochemical devices (32) (see Photovoltaic cells). 

It is well knovm, that in chloroplast thylakoid membrane the absorption of light induces a veaorial electron transfer through the two photosystems in a sequential process involving the formation of red-ox species. The use of a one compartment three electrode photoelectrochemical cell, first designed by Allen and Crane and successively modified by Carpentier et al, can allow these species to be revealed, if they are dissolved in the aqueous phase. The CV is, indeed, a powerfijl technique for detection of reactions proceeding, following or interposed between electron transfer to the electrode. 

In the water photolysis system composed of an aqueous solution of colloidal Prussian Blue (PB, see Sect. 5.1) and Ru(bpy) 413,414) photoinduced electron transfer was considered to occur with electrons being transferred from the excited Ru complex adsorbed on the PB colloidal particle to the PB. Such a photochemical reaction must also be applicable to the coated electrode system used for photogalvanic cells. This kind of coated electrode system for photoelectrochemical conversion must in addition give information on heterogeneous photochemical reactions. Thus a basal plane pyrrolytic graphite (BPG) electrode was first coated with a polymer-pendant Ru(bpy)3 (7) membrane and then with a PB membrane by reductive electrodeposition from the aqueous mixture of Fe(CN) and Fe . The bilayer-coated system... 

In the dye-sensitized photoelectrochemical cell [7], the dye molecule in the photoelectrode absorbs visible light radiations. Absorption of the visible light photon causes an excitation of electrons which are carried toward the counter electrode for the reduction reaction. This transfer of electrons takes place via conduction wires. The oxidation reaction takes place at the photoanode. The dye can be regenerated after receiving electrons from water molecule or water oxidation process. 

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