Engineering Olefin-Linked Covalent Organic Frameworks for Photoenzymatic Reduction of CO 2 .

It is of profound significance concerning the global energy and environmental crisis to develop new techniques that can reduce and convert CO 2 . To address this challenge, we built a new type of artificial photoenzymatic system for CO 2 reduction, using a rationally designed mesoporous olefin-linked covalent organic framework (COF) as the porous solid carrier for co-immobilizing formate dehydrogenase (FDH) and Rh-based electron mediator. By adjusting the incorporating content of the Rh electronic mediator, which facilitates the regeneration of nicotinamide cofactor (NADH) from NAD + , the apparent quantum yield can reach as high as 9.17±0.44 %, surpassing all reported NADH-regenerated photocatalysts constructed by crystalline framework materials. Finally, the assembled photocatalyst-enzyme coupled system can selectively convert CO 2 to formic acid with high efficiency and good reusability. This work demonstrates the first example using COFs to immobilize enzymes for artificial photosynthesis systems that utilize solar energy to produce value-added chemicals.