Highly Efficient CO2 Reduction Using Metal Complexes as Photocatalyst

Highly efficient photocatalytic CO2 reduction using metal complexes, particularly rhenium(I) bipyridine complexes, is reviewed. Importance about development of such CO2 reduction photocatalysts is explained from the points of both problems with global warming and shortage of fossil fuels. Recent progress in photocatalysts for CO2 reduction has been achieved using the following systems and methods: (1) introduction of a phosphine ligand to rhenium(I) mononuclear complexes, (2) a mixed system of two rhenium(I) complexes, of which quantum yield for CO2 reduction reaches up to 59%, (3) introduction of interligand weak (pi-pi and CH-pi) interaction into rhenium(l) complexes, and (4) supramolecular photocatalysts constructed with both Ru(II) and Re(I) complexes, which can efficiently use a wide range of visible light.