Photocatalytic Reduction of Low Concentration of CO2

A novel molecular photocatalytic system with not only high reduction ability of CO 2 but also high capture ability of CO 2 has been developed using a Ru(II)-Re(I) dinuclear complex as a photocatalyst. By using this photocatalytic system, CO 2 of 10% concentration could be selectively converted to CO with almost same photocatalysis to that under a pure CO 2 atmosphere (TON CO > 1000, Φ CO > 0.4). Even 0.5% concentration of CO 2 was reduced with 60% initial efficiency of CO formation by using the same system compared to that using pure CO 2 (TON CO > 200). The Re(I) catalyst unit in the photocatalyst can efficiently capture CO 2 , which proceeds CO 2 insertion to the Re-O bond, and then reduce the captured CO 2 by using an electron supplied from the photochemically reduced Ru photosensitizer unit.