Combination of Organic Dye and Iron for CO 2 Reduction with Pentanuclear Fe 2 Na 3 Purpurin Photocatalysts.

Molecular photocatalysts designed with earth-abundant elements are rare and challenging in artificial photosynthesis study. Herein, we report a multimetallic Fe 2 Na 3 purpurin ( 1 ) complex for the reduction of CO 2 in DMF under visible-light irradiation. The photocatalytic system achieves 91% selectivity and 2625 ± 334 turnovers of CO in 120 h, which is among the highest reported for a noble-metal-free catalyst without an additional photosensitizer. UV-vis and electrochemical studies suggest that the mechanism involves subsequent reductions and protonations of 1 to generate [Fe II 2 Na 3 ( (H)2 PP) 6 ] 5- and [Fe III 2 Na 3 ( (H)2 PP) 6 ] 3- as the active photocatalysts in CO 2 reduction.