VISIBLE-LIGHT-INDUCED AND LONG-LIVED CHARGE SEPARATION IN A TRANSPARENT NANOSTRUCTURED SEMICONDUCTOR MEMBRANE MODIFIED BY AN ADSORBED ELECTRON-DONOR AND ELECTRON-ACCEPTOR

The preparation of transparent nanostructured TiO2 (anatase) membranes is described. Detailed characterization shows these membranes to be 5 0 mu m thick nanoporous-nanocrystalline structures with associated val ues for porosity and surface roughness of 50% and 5000, respectively. Modification of these membranes by coadsorption of a ruthenium complex , bis ine)(4,4'-dimethyl-2,2'-bipyridine)-ruthenium(II)] dichloride (I ), and of a viologen, -carboxy-3-hydroxyphenyl)methyl]-4,4'-bipyridini um perchlorate (II), is also described. Detailed studies show that vis ible-light-induced electron transfer by electronically excited I to th e conduction band of the nanostructured TiO2 membrane is followed by m embrane mediated electron transfer to coadsorbed II. Detailed studies also show that, as a consequence of the rectifying properties of the s emiconducting membrane, charge separation is long-lived, The possible significance of these findings for the development of a practical wate r splitting device is considered.