本文要点：
在有机半导体或纳米碳领域，多环芳烃(PAHs)作为单个分子或结构单元占据主导地位。经由sp2-碳桥连接PAHs以形成高结晶的p-延伸结构不仅对于扩大二维材料的范围而且对于实现优异的性质/功能都是非常期望的。
在这项工作中，作者开发了5,10-二甲基-4,9-二氮杂蒽作为关键单体，它的两个甲基在氮原子附近，可以帮助增加溶解度，并作为活性连接位点。
在有机酸的存在下，这种单体能够顺利进行Knoevenagel缩合，形成两个亚乙烯基连接的PAH核COFs，它们显示出高结晶蜂窝状结构，具有高达1238 m2 g-1的大表面积。
由于PAH结构单元与亚乙烯基的直接连接方式，所制备的COFs具有空间延伸的p共轭和显著的半导体性质。因此，它们的可见光光催化具有优异的活性和耐久性，在纯水中可产生高达3820 µmol g-1 h-1的H2O2，使用苯甲醇作为空穴牺牲剂甚至可产生17080 µmol g-1 h-1的H2O2。
Figure 1.(a) Synthesis of the key monomer DMDP and model compound DMDP-MDL. (b) Single crystal structures of DMDP and DMDP-MDL in top and side views. (c) Schematic diagram of synthesis of the target COFs, g-COF-DMDP-1 and g-COF-DMDP-2.
Figure 2. PXRD Patterns of (a) g-COF-DMDP-1 and (b) g-COF-DMDP-2. Middle: the corresponding refined eclipsed AA stacking structures of g-COF-DMDP-1 and g-COF-DMDP-2. (c) FT-IR spectra of g-COF-DMDP-1 and g-COF-DMDP-2. (d)13C NMR spectra of g-COF-DMDP-1, g-COF-DMDP-2, model molecule DMDP-MDL.
Figure 3. (a) HRTEM image of g-COF-DMDP-1 with observable crystalline areas. (b) The enlarged view of the selected area indicates the distance of (100) planes. Upper right: fast Fourier transform (FFT) pattern. (c) Nitrogen adsorption and desorption isotherms of g-COF-DMDP-1 and g-COF-DMDP-2 at 77 K. (d) Pore-size distribution profiles of g-COF-DMDP-1 and g-COF-DMDP-2.
Figure 4.(a) UV-vis DRS patterns of g-COF-DMDP-1 and g-COF-DMDP-2. Inside: the digital photographs of the samples under ambient light. (b) Band structure diagrams of g-COF-DMDP-1 and g-COF-DMDP-2. (c) EPR spectra of g-COF-DMDP-1 and g-COF-DMDP-2 under dark and light irradiation. (d) Transient photocurrents of g-COF-DMDP-1 and g-COF-DMDP-2 under visible light irradiation. (e) EIS spectra of g-COF-DMDP-1 and g-COF-DMDP-2 in the dark and under visible light irradiation. (f) Water contact angles of g-COF-DMDP-1 and g-COF-DMDP-2. (g) Time profiles of H2O2 production for g-COF-DMDP-1 and g-COF-DMDP2. (h) Photocatalytic H2O2 production performance using g-COF-DMDP-1 and g-COF-DMDP-2 in the presence of various scavengers. (i) EPR spectra of g-COFDMDP-1 and g-COF-DMDP-2 in the dark and under visible light, using DMPO as the spin-trapping agent.
https://doi.org/10.1002/anie.202418895
