Photo-generated dinuclear {Eu(II)}2 active sites for selective CO2 reduction in a photosensitizing metal-organic framework

Abstract

Photocatalytic reduction of CO₂ is a promising approach to achieve solar-to-chemical energy conversion. However, traditional catalysts usually suffer from low efficiency, poor stability, and selectivity. Here we demonstrate that a large porous and stable metal-organic framework featuring dinuclear Eu(III)₂ clusters as connecting nodes and Ru(phen)₃-derived ligands as linkers is constructed to catalyze visible-light-driven CO₂ reduction. Photo-excitation of the metalloligands initiates electron injection into the nodes to generate dinuclear {Eu(II)}₂ active sites, which can selectively reduce CO₂ to formate in a two-electron process with a remarkable rate of 321.9 μmol h⁻¹ mmol_MOF⁻¹. The electron transfer from Ru metalloligands to Eu(III)₂ catalytic centers are studied via transient absorption and theoretical calculations, shedding light on the photocatalytic mechanism. This work highlights opportunities in photo-generation of highly active lanthanide clusters stabilized in MOFs, which not only enables efficient photocatalysis but also facilitates mechanistic investigation of photo-driven charge separation processes.