Effects of Ag-photodeposition on photocurrent of an ITO electrode modified by a hybrid film of TiO2 nanosheets

We performed the photodeposition of Ag clusters onto a TiO2 nanosheet hybridized with an amphiphlic Ru(II) complex (denoted by TiO2-Ru/Ag). Firstly a floating monolayer of [Ru(phen)(2)(dC18bPY)](ClO4)(2) (phen = 1,10-phenanthroline, dC18bpy = 4,4'-dioctadecyl-2,2'-bipyridyl) was formed on an aqueous dispersion of exfoliated layered titanate, (TBAOH)(x) Ti(2-x/4)square(x/4)O(4).H2O (x similar to 0.7: square, vacancy; TBAOH = tetrabutylammonium hydroxide) (denoted as TiO2 nanosheet). The monolayer acted as the organic part for the hybridization of TiO2 particles in an aqueous phase. A hybrid film of TiO2 nanosheet and an amphiphilic metal complex (denoted by TiO2-Ru) was transferred onto an indium tin oxide substrate by the vertical dipping method. Thereafter the electrode was immersed in 1.0 M AgNO3 for 10 min and rinsed with water. The electrode was irradiated for 30 mill by a Xe-lamp (150 W). Atomic force microscope, X-ray photoelectron spectra and cyclic voltammometry showed the formation of silver nanoparticles with a radius of 20-150 nm. The photocurrent response was measured in the potential range of 0.2-1.2 V (vs. Ag\AgCl\KCl(sat)) under the illumination of light (>350 nm). The current increased 1.7 times when the layer number of hybrid films increased from one to two. It should be emphasized that such an increase of photocurrent with a layer number was not observed in the absence of Ag particles. (C) 2003 Elsevier B.V. All rights reserved.