The visible-light-driven photocatalytic CO₂ reduction with high efficiency is highly desirable but challenging. Herein, we present porphyrin-tetraphenylethene-based covalent organic frameworks (MP-TPE-COF, where M=H₂, Co and Ni; TPE=4,4′,4″,4‴-(ethane-1,1,2,2-tetrayl) tetrabenzaldehyde; COF=covalent organic framework) as ideal platforms for understanding photocatalytic CO₂ reduction at molecular level. Experimental and theoretical investigations have demonstrated crucial roles of metalloporphyrin units in selective adsorption, activation and conversion of CO₂ as well as in the separation of charge carriers and electron transfer, thus allowing for flexible modulation of photocatalytic activity and selectivity. CoP-TPE-COF exhibits high CO evolution rate of 2,414 µmol g⁻¹ h⁻¹ with the selectivity of 61% over H₂ generation under visible-light irradiation, while NiP-TPE-COF provides CO evolution rate of 525 µmol g⁻¹ h⁻¹ and 93% selectivity with superior durability. Moreover, the photocatalytic system is feasible for the simulated flue gas, which provides CO evolution rate of 386 µmol g⁻¹ h⁻¹ and selectivity of 77%. This work provides in-depth insight into the structure-activity relationships toward the activation and photoreduction of CO₂.

高效地期望可见光驱动的光催化CO ₂还原，但是具有挑战性。在这里，我们提出了基于卟啉-四苯乙烯的共价有机骨架（MP-TPE-COF，其中M = H ₂，Co和Ni； TPE = 4,4'，4″，4′-（乙烷-1,1,2 （2-2-四基）四苯甲醛； COF ＝共价有机骨架）作为理解分子水平上光催化CO ₂还原的理想平台。实验和理论研究证明了金属卟啉单元在选择性吸附，活化和转化CO _2中的关键作用以及在分离载流子和电子时，因此可以灵活调节光催化活性和选择性。COP-TPE-COF表现出2414的高CO释放速率微摩尔克^-1 ħ ^-1 61％较H的选择性₂代可见光照射下，而NiP的-TPE-COF提供的525微摩尔克CO释放速率^{- 1} h ^-1和93％的选择性，具有出色的耐久性。此外，光催化系统对于模拟烟道气是可行的，其提供的CO释放速率为386 µmol g ^-1 h ^-1选择性为77％。这项工作提供了对CO ₂活化和光还原的构效关系的深入了解。