Solar reduction of water. I. Competition between light-induced hydrogen formation and hydrogenation of methylviologen in the system water-Tris(2,2'-bipyridine)ruthenium dication-ethylenediaminetetraacetic acid-platinum

The light-induced formation of hydrogen in the system H2O-Ru(bpy)32+-mv2+-edta-Pt (mv, inethylviologen) is accompanied by the hydrogenation of mv2+ to give the 1-methyl-4-(1'-methylpiperidin-4'-yl)pyridinium cation (1). The production of hydrogen is decreased by factors that favour the formation of this cation. The extent of hydrogenation depends on the pH of the mixture, the amount and type of catalyst present, and the partial pressure of hydrogen during irradiation.