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)xTi2−x/4□x/4O4 · H2O (x∼0.7;□, 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 min 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.