Metal-Organic Frameworks Significantly Enhance Photocatalytic Hydrogen Evolution and CO_2 Reduction with Earth-Abundant Copper Photosensitizers

摘要

We report here the design of two multifunctional metal—organic frameworks (MOFs), mPT-Cu/Co and mPT-Cu/ Re comprising cuprous photosensitizers (Cu-PSs) and molecular Co or Re catalysts for photocatalytic hydrogen evolution (HER) and CO_2 reduction (CO_2RR), respectively. Hierarchical organization of Cu-PSs and Co/Re catalysts in these MOFs facilitates multielectron transfer to drive HER and CO_2RR under visible light with an HER turnover number (TON) of 18 700 for mPT-Cu/ Co and a CO_2RR TON of 1328 for mPT-Cu/Re, which represent a 95-fold enhancement over their homogeneous controls. Photophysical and electrochemical investigations revealed the reductive quenching pathway in HER and CO_2RR catalytic cycles and attributed the significantly improved performances of MOFs over their homogeneous counterparts to enhanced electron transfer due to close proximity between Cu-PSs and active catalysts and stabilization of Cu-PSs and molecular catalysts by the MOF framework.