Sustainable and clean energy resources are required in order to solve global energy and environmental issues. Extensive efforts have so fat been devoted to realize artificial photosynthesis for sustainable fuel production. Artificial photosynthesis consists of light harvesting, charge-separation and catalytic processes for water oxidation and reduction as well as CO2 fixation unit.1 This lecture focuses on photocatalytic oxidation processes in artificial photosynthesis.
Catalytic water oxidation to generate oxygen has been achieved using all-inorganic mononuclear ruthenium complexes bearing Keggin-type lacunary heteropolytungstate, as catalysts with (NH4)2[CeIV(NO3)6] as a one-electron oxidant in water. The overall catalytic mechanism of water oxidation was revealed based on the kinetic analysis and detection of the catalytic intermediates.2 We have also developed highly efficient photocatalytic olefin epoxidation and alkane hydroxylation by using manganese porphyrins as catalysts, [Ru(bpy)3]2+ (bpy = 2,2’-bipyridine) as a photosensitizer, [CoIII(NH3)5Cl]2+ as a weak one-electron oxidant, and water as an oxygen source.3 The photocatalytic water oxidation to produce hydrogen peroxide as a chemical fuel will also be reported.
(1) Fukuzumi, S.; Kojima. T. J. Mater. Chem. 2008, 18, 1427.
(2) Murakami, M.; Hong, D.; Suenobu, T.; Fukuzumi, S. J. Am. Chem. Soc. 2011, 133, 11605.
(3) Fukuzumi, S.; Kishi, T.; Kotani, H.; Lee, Y.-M.; Nam, W. Nature Chem. 2011, 3, 38.