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Alkene-Linked Covalent Organic Frameworks Boosting Photocatalytic Hydrogen Evolution by Efficient Charge Separation and Transfer in the Presence of Sacrificial Electron Donors.
Advanced Science ( IF 14.3 ) Pub Date : 2020-05-06 , DOI: 10.1002/advs.201902988
Chunshao Mo 1 , Meijia Yang 1 , Fusai Sun 1 , Junhua Jian 1 , Linfeng Zhong 1 , Zhengsong Fang 1 , Jiangshan Feng 1 , Dingshan Yu 1
Affiliation  

Covalent organic frameworks (COFs) are potential photocatalysts for artificial photosynthesis but they are much less explored for photocatalytic hydrogen evolution (PHE). COFs, while intriguing due to crystallinity, tunability, and porosity, tend to have low apparent quantum efficiency (AQE) and little is explored on atomistic structure–performance correlation. Here, adopting triphenylbenzene knots and phenyl linkers as a proof of concept, three structurally related COFs with different linkages are constructed to achieve a tunable COF platform and probe the effect of the linkage chemistry on PHE. Cyano‐substituted alkene‐linked COF (COF–alkene) yields a stable 2330 µmol h−1 g−1 PHE rate, much superior to imine‐ and imide‐linked counterparts (<40 µmol h−1 g−1) under visible light irradiation. Impressively, COF–alkene achieves an AQE of 6.7% at 420 nm. Combined femtosecond transient absorption spectroscopy and theoretical calculation disclose the critical role of cyano‐substituted alkene linkages toward high efficiency of charge separation and transfer in the presence of sacrificial electron donors—the decisive key to the superior PHE performance. Such alkene linkages can also be extended to design a series of high‐performance polymeric photocatalysts, highlighting a general design idea for efficient PHE.

中文翻译:

烯烃连接的共价有机框架通过在牺牲电子供体存在下的有效电荷分离和转移来促进光催化析氢。

共价有机骨架(COF)是人工光合作用的潜在光催化剂,但在光催化析氢(PHE)方面的探索却少得多。COF 虽然由于结晶度、可调谐性和孔隙率而令人感兴趣,但往往具有较低的表观量子效率 (AQE),并且对原子结构与性能相关性的探索很少。在这里,采用三苯基苯结和苯基连接子作为概念证明,构建了三个具有不同键的结构相关的COF,以实现可调谐的COF平台,并探讨键化学对PHE的影响。氰基取代的烯烃连接的COF(COF-烯烃)在可见光下产生稳定的2330 µmol h -1 g -1 PHE速率,远优于亚胺和酰亚胺连接的对应物(<40 µmol h -1 g -1 )辐照。令人印象深刻的是,COF-烯烃在 420 nm 处的 AQE 达到 6.7%。结合飞秒瞬态吸收光谱和理论计算揭示了氰基取代的烯烃键在牺牲电子供体存在下对高效率电荷分离和转移的关键作用——这是优异 PHE 性能的决定性关键。这种烯烃键还可以扩展到设计一系列高性能聚合物光催化剂,突出了高效板式换热器的总体设计理念。
更新日期:2020-06-24
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