Metal–Organic Frameworks Significantly Enhance Photocatalytic Hydrogen Evolution and CO2 Reduction with Earth-Abundant Copper Photosensitizers

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 2 RR), respectively. Hierarchical organization of Cu-PSs and Co/Re catalysts in these MOFs facilitates multielectron transfer to drive HER and CO 2 RR under visible light with an HER turnover number (TON) of 18 700 for mPT-Cu/Co and a CO 2 RR 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 2 RR 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.