Partners and International Organizations
(English)
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A, B, BG, CZ, DK, FIN, F, D, HR, IRL, I, LV, NL, PL, P, RO, SI, E, S, CH, GB
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Abstract
(English)
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The organisation and the photoreactivity of metal and semiconductor nanoparticles have been investigated at polarisable liquid/liquid interface by means of different spectro and photo-electrochemical techniques. By employing naked TiO2 at water/dichloroethane (DCE) interface, it is possible to reduce or oxidise molecular species in organic or aqueous depending on the pH. However, TiO2 as a photocatalyst requires photon energy greater than 3.1 eV. Therefore, studies were also undertaken with dye-sensitized TiO2 nanoparticles assembled at water/DCE interface to extend the response in the visible part. Photocurrent responses associated with the photooxidation of ferrocene in DCE were observed in the presence of TiO2 colloids sensitised with chlorin e-6, catechol and alizarin in the aqueous phase. Interfacial sensitisation was also observed by introducing the hydrophobic dye alizarin in the DCE phase. The voltage-induced assembly of mercaptosuccinic acid-stabilized Au nanoparticles of 1.5 nm in diameter has been investigated as well at the polarizable water 1,2-dichloroethane interface. The density of gold nanoparticles can be effectively tuned by the applied potential bias. Admittance measurements and quasi-elastic laser scattering (QELS) studies revealed that the surface concentration of the nanoparticle at the liquid/liquid boundary can be reversibly controlled by the applied bias potential. The electrochemical and optical measurements provide no evidence of irreversible aggregation or deposition of the particles at the interface. Analysis of the electrocapillary curves constructed from the frequency dependence of the capillary waves on the applied potential and bulk particle concentration indicates that the maximum particle surface density is 3.8 1013 cm-2, which corresponds to 67% of a square closed pack arrangement. Finally, the photoreactivity of semiconductor quantum dots (CdSe) under applied bias are currently studied at the liquid/liquid interface. Analysis of the photocurrent response as a function of the applied potential and the formal redox potential of the organic phase quencher suggest that deeply trapped electrons are involved in the heteregeneous charge transfer process.
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