Photoelectrochemical water splitting using coumarin based ruthenium(II) catalyst

Photoelectrochemical water splitting with assistance of solar light for hydrogen production has been deemed as a rather promising route to ameliorate the increasing energy crisis. In a dye-sensitized photoelectrochemical cell (DSPEC) for water splitting, water is converted into O₂ at the anode while the cathode is used to produce H₂ from water, or convert CO₂ into reduced hydrocarbon products. Traditionally, these devices are constructed where water oxidation occurs at a photoanode comprised of a semiconductor with an adsorbed water oxidation catalyst (sensitizer). Ruthenium(II) complexes exhibit the lowest overpotentials for water oxidation and highest turnover frequencies even matching the oxygen evolution rates in the oxygen-evolving complex of Photosystem II making them ideal for use in DSPEC photoanodes. We describe here a novel, economical and robust synthesis of Ruthenium(II) catalyst containing coumarin based 8-hydroxyquinoline ligand, 3-((E)-(8hydroxyquinolin- 5-ylimino)methyl)-4-chloro-2H-chromen-2-one