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

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 mu mol 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 photogeneration 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.