Preparation, characterization, and photoelectric properties of an electrostatically self-assembled film based on colloidal tungsten trioxide and a dinuclear Ru(II) complex

An electrostatic self-assembled film based on a tungstic acid colloidal solution and a dinuclear Ru(II) complex [(bpy)2Ru(bpbh)Ru(bpy)2](CIO4)4 [where bpy = 2,2'-bipyrizine and bpbh = 1,6-bis-(2-(2-pyridyl)benzimidazoyl)hexane] has been prepared and characterized by means of ultraviolet-visible absorption and emission spectroscopy and cyclic voltammetry. The photoelectrochemical properties of the films have also been studied. A large anodic photocurrent of 0.8 microA/cm2 was observed when a monolayer film of ITO/WO3/the Ru complex was irradiated with polychromatic light (730 nm > lambda > 325 nm) at a positive applied potential of 0.6 V versus a saturated calomel electrode, four-fold that observed under the same experimental condition for the ITO electrode covered with only a monolayer of WO3 without the Ru(II) complex, indicating that the the anodic photocurrent mainly arose from the electron injection from the photoexcited Ru(II) complex to the conduction band of WO3.