Water Photolysis by Means of Visible Light with a System Composed of Prussian Blue and the Tris(2,2′-bipyridine)ruthenium(II) Complex

Abstract

Abstract A water-photolysis system composed of Prussian Blue (PB) and the tris(2,2′-bipyridine)ruthenium(II) complex([Ru(bpy)3]2+)which evolves hydrogen and oxygen simultaneously was studied. Both the components worked catalytically in the photolysis. PB provides active sites for both H2 and O2 evolution. The dependence on the pH showed optimum conditions at pH 2. The photolysis required the presence of a cation, and only such cations as K+ and Rb+ whose hydrated ions are smaller than the pore size of the PB lattice were active for the reaction. The dependene on the KCl concentraition showed an optimum point at 0.5 mol dm−3. The oxidative quenching of [Ru(bpy)3]2+* by PB was suggested, but its ratio in the total quenching process was estimated to be only 8.5%. The static quenching of [Ru(bpy)3]2+* by PB was demonstrated, and an interaction between the two components was shown by NMR spectroscopy. The effect of oxygen on the photolysis suggested that the reduction sites are located inside the PB lattice. A mechanism for the photolysis was proposed.