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

Abstract

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) ([(NH ₃ ) ₅ Ru(µ-O)Ru (NH ₃ ) ₄ (µ-O)Ru(NH ₃ ) 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.