Dioxygen evolution induced by visible light at layered sensitizer water oxidation catalyst

Photoelectrocatalytic water oxidation was investigated using a multilayer-modified electrode composed of a Nafion (Nf)) membrane incorporating tris(2,2'-bipyridine)ruthenium(II) ([Ru(bpy)(3)](2+)) sensitizer and an electrodeposited platinum black (Pt-black) adsorbing trinuclear ruthenium complex (Ru-red) ([(NH3)(5)Ru(mu-O)Ru (NH3)(4)(mu-O)Ru(NH3)(5)](6+)) as a water oxidation catalyst. In this multilayered indium tin oxide (ITO)/Nf [Ru(bpy)(3)(2+)]/Pt-black[Ru-red] system, an anodic photocurrent was generated induced by photoexcitation of [Ru(bpy)(3)](2+). This anodic photocurrent was much higher than that generated without Ru-red. Dioxygen evolution was also induced by visible light at anodic applied potentials, which was ascribed to rapid transfer of positive charge from [Ru(bpy)(3)](3+) to Ru-red where water oxidation takes place.