Construction of Covalent Organic Frameworks with Partly Condensed Networks for Photocatalytic Hydrogen Evolution
Construction of Covalent Organic Frameworks with Partly Condensed Networks for Photocatalytic Hydrogen Evolution
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DOI：
10.1021/acsaem.3c01379
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发表时间：
2023-08
影响因子：
6.4
通讯作者：
Chao Gao;X. Zhang;Menghui Zhang;Xiao Wu;Rufan Chen;Chong Zhang;Chengguo Sun;Yang Du;
中科院分区：
文献类型：
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作者：
Chao Gao;X. Zhang;Menghui Zhang;Xiao Wu;Rufan Chen;Chong Zhang;Chengguo Sun;Yang Du;
共价有机框架（COF）通常通过拓扑定向缩合反应设计以形成含有相应顶点和边缘连接基单元的所需网络。一般来说，框架中的构件总是与框架互补和充分连接。在本工作中，我们设计并合成了两种由相同单体构建的COF，TPE-TPB-A和TPE-TPB-B。两者均具有良好的结晶性和相似的BET比表面积，但不同的XRD图谱。结合结构模拟和实验数据，确定TPE-TPB-A通过正常的完全键合[4 + 4]途径连接，而TPE-TPB-B通过不寻常的[4 + 2]途径连接，其中未反应的悬挂甲酰基基团。更重要的是，具有暴露的甲酰基的部分缩合的TPE-TPB-B比完全缩合的TPE-TPB-A表现出更有利的物理/化学性质用于光催化析氢（PHE），例如改善的亲水性和更好的电荷分离和传输。值得注意的是，TPE-TPB-B的平均PHE速率被测量为在可见光照射下比TPE-TPB-A的平均PHE速率高10倍以上，其中铂作为助催化剂，抗坏血酸作为牺牲剂。这些结果为各种应用开辟了部分冷凝COF的可能性。
Covalent organic frameworks (COFs) are typically designed by topologically directed condensation reactions to form the desired networks containing the respective vertex and edge linker units. In general, the building blocks in the frameworks are always complementarily and fully connected to the frameworks. In this work, we showed the design and synthesis of two COFs, TPE-TPB-A and TPE-TPB-B, which were constructed from the same monomers. Both exhibited good crystallinity and similar BET specific surface area but different XRD patterns. Combined with structure simulation and experimental data, TPE-TPB-A was determined to be connected by a normal fully bonded [4 + 4] pathway, while TPE-TPB-B was constructed via an unusual [4 + 2] pathway with unreacted dangling formyl groups. More importantly, partly condensed TPE-TPB-B with exposed formyl groups exhibited more favorable physical/chemical properties than fully condensed TPE-TPB-A for photocatalytic hydrogen evolution (PHE), such as improved hydrophilicity and better charge separation and transportation. Remarkably, the average PHE rate of TPE-TPB-B was measured to be more than 10 times higher than that of TPE-TPB-A under visible-light irradiation with platinum as a cocatalyst and ascorbic acid as a sacrificial agent. These results open up possibilities toward partly condensed COFs for various applications.