An artificial light-harvesting supramolecule with a Ru₄Cu₂ core for efficient CO₂ photoreduction

Developing highly efficient photocatalysts for converting carbon dioxide (CO₂) into valuable chemical fuels is crucial for the effective utilization of carbon resources. Herein, we report the construction of an efficient artificial light-harvesting system with a multimetallic Ru₄Cu₂ core for photocatalytic CO₂ reduction. In this system, four photosensitive Ru(II) antennas, Ru(bpy)₂(H₂biim) (bpy = 2,2'-bipyridine, H₂biim = 2,2'-biimidazole), were coordinated with two catalytically active Cu(II) centers, forming the Ru₄Cu₂ coordination supermolecule with strong light-harvesting ability. Upon visible light irradiation, the Ru₄Cu₂ supramolecule exhibited remarkable gas-solid phase CO₂ photoreduction activity with an excellent CO evolution rate of 88.69 μmol g^-1 h^-1. In contrast, the replacement of Cu(II) with Co(II) or Ni(II) showed a decrease in the CO release rate, indicating the unique and efficient catalytic ability enabled by the introduction of the Cu(II) center. The experimental investigations combined with theoretical calculations revealed a synergistic effect between the photosensitive Ru(II) and catalytic Cu(II) centers, facilitating electron transfer and boosting the photocatalytic performance. This work provides a comprehensive understanding of the mechanisms underlying artificial photocatalysts.