Photo-generated dinuclear {Eu(II)}<sub>2</sub> active sites for selective CO<sub>2</sub> reduction in a photosensitizing metal-organic framework.

Yan, Zhi-Hao; Du, Ming-Hao; Liu, Junxue; Jin, Shengye; Wang, Cheng; Zhuang, Gui-Lin; Kong, Xiang-Jian; Long, La-Sheng et al. · Nat Commun · 2018

basic_science · Level V

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Abstract

Photocatalytic reduction of CO<sub>2</sub> 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)<sub>2</sub> clusters as connecting nodes and Ru(phen)<sub>3</sub>-derived ligands as linkers is constructed to catalyze visible-light-driven CO<sub>2</sub> reduction. Photo-excitation of the metalloligands initiates electron injection into the nodes to generate dinuclear {Eu(II)}<sub>2</sub> active sites, which can selectively reduce CO<sub>2</sub> to formate in a two-electron process with a remarkable rate of 321.9 μmol h<sup>-1</sup> mmol<sub>MOF</sub><sup>-1</sup>. The electron transfer from Ru metalloligands to Eu(III)<sub>2</sub> 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.