Highly efficient visible-light-driven CO2 reduction to CO using a Ru(ii)–Re(i) supramolecular photocatalyst in an aqueous solution

Abstract

In an aqueous solution, [Ru(dmb)₂–(BL)–Re(CO)₃Cl]²⁺ (BL = bridging ligand) most efficiently photocatalyzed the reduction of CO₂ to CO under visible-light irradiation using 2-(1,3-dimethyl-2,3-dihydro-1H-benzimidazol-2-yl)benzoic acid (BI(CO₂H)H) as a water-soluble sacrificial reductant (Φ_CO = 13%, TON = 130). Since BI(CO₂H)H could efficiently produce one-electron-reduced species of [Ru(diimine)₃]²⁺-type complexes under visible-light irradiation even in an aqueous solution, that is one of the main reasons why the photocatalytic system induced the highly efficient CO₂ reduction. This result strongly indicates that BI(CO₂H)H should be a useful reductant for evaluating the real abilities of various photocatalytic systems in water as well.