Photo-induced water oxidation with tetra-nuclear ruthenium sensitizer and catalyst: A unique 4 × 4 ruthenium interplay triggering high efficiency with low-energy visible light

Water oxidation poses a formidable challenge being the energy-demanding bottleneck of artificial photosynthesis. According to a modular photosynthetic approach, oxidation of H2O to O2 is the key source of electrons and protons powering the reductive half-reaction, where hydrogen is produced. H2 is the most sought alternative to carbon fuels. As the global need for benign and renewable energy sources becomes urgent, photoinduced water oxidation is at the center of an ever-growing research effort. Here we report the combined use of a tetranuclear Ru(II) dendrimeric photosensitizer and of a tretraruthenium substituted polyoxotungstate as the catalyst (a otally inorganic oxygen evolving complex) that enables photo-induced water oxidation at 550 nm producing molecular oxygen from water with an outstanding quantum yield of 0.30.