Effects of Ag-photodeposition on photocurrent of an ITO electrode modified by a hybrid film of TiO 2 nanosheets

Abstract

We performed the photodeposition of Ag clusters onto a TiO 2 nanosheet hybridized with an amphiphlic Ru(II) complex (denoted by TiO 2–Ru/Ag). Firstly a floating monolayer of [Ru(phen) 2(dC18bpy)](ClO 4) 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 □ x/4 O 4 · H 2O ( x∼0.7;□, vacancy; TBAOH = tetrabutylammonium hydroxide) (denoted as TiO 2 nanosheet). The monolayer acted as the organic part for the hybridization of TiO 2 particles in an aqueous phase. A hybrid film of TiO 2 nanosheet and an amphiphilic metal complex (denoted by TiO 2–Ru) was transferred onto an indium tin oxide substrate by the vertical dipping method. Thereafter the electrode was immersed in 1.0 M AgNO 3 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.