A molecular water-reduction catalyst: surface derivatization of titania colloids and suspensions with a platinum complex

The authors report here the first example of the surface derivatization of a semiconductor with a platinum bipyridyl complex. This complex was formed in situ by either direct excitation or photosensitization of TiO{sub 2} particles in the presence of (Pt(bpy){sub 2}){sup 2+} (where bpy = 2,2{prime}-bipyridine) and a sacrificial electron donor in aqueous media. Optical and x-ray photoelectron spectroscopy (XPS) measurements provided detailed information about the nature of the complex and its attachment to the surface of TiO{sub 2}. The surface complex exhibited relatively high activity in the photoreduction of water compared with that of conventional platinized TiO{sub 2} systems.