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

利用太阳光驱动CO2还原不仅可降低大气中CO2浓度，而且可以生成重要的化工原料，是缓解气候变暖和开发新能源的理想途径之一。然而如何制备高效光催化剂将CO2高选择性地转化为高附加值的化学产品极具挑战性。课题组巧妙地将具有催化活性的稀土簇合物与光敏配体组装在一起，合成了具有大孔结构的稀土Eu-Ru(phen)3-MOF催化剂，实现了可见光驱动的CO2到甲酸盐的高效选择性转化。研究表明，该材料光催化生成甲酸盐的反应速率可达到321.9 μmol h−1 mmolMOF−1，这是至今为止报道的光催化还原CO2转化为甲酸盐活性最高的MOFs催化剂。 该项研究工作由博士生闫志浩完成，博士生杜明浩参与部分表征工作；中国科学院大连化学物理研究所金盛烨研究员、刘俊学博士在瞬态光谱表征中给予了支持；我校化学化工学院汪骋教授在数据分析过程中给予大量帮助；理论计算由浙江工业大学庄桂林副教授完成。【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 321.9μmolh −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.We are grateful for the financial support from the 973 project (Grant 2014CB845601) of the Ministry of Science and Technology of China, the National Natural Science Foundation of China (Grants no. 21422106, 21673184, 21431005, 21721001, and 21390391) and the Fok Ying Tong Education Foundation (151013). We thank Dr. Wen-Ming Qin and the staffs from the BL17B beamline of National Center for Protein Sciences Shanghai at Shanghai Synchrotron Radiation Facility for assistance during data collection; we also thank Miss Ying-Zi Han for helpful measurement on ESI-MS. We also gratefully acknowledge Mr Xuefu Hu for helpful measurement on time-resolved PL and Miss Rong Chen for her assistance on CV measurement and analysis. 研究工作得到科技部（项目批准号：2014CB845601）、国家自然科学基金委（项目批准号：21422106、21673184、21431005、21721001、21390391）、教育部霍英东基金会青年教师基金（项目批准号：151013）等资助