第一作者：Xu Chi
通讯作者：上海交通大学 张帆
DOI：https://doi.org/10.1002/anie.202418895
多环芳烃（PAHs）在有机半导体或纳米碳领域中，无论是作为单个分子，还是作为构建单元，都占据着主导地位。通过sp2-碳桥连接多环芳烃形成高结晶π-扩展结构，不仅可以扩大二维材料的范围，而且可以实现特殊的性能/功能。作者开发了5,10-二甲基-4,9-二氮杂芘作为关键单体，其相邻氮原子的两个甲基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，该单体能够顺利地进行Knoevenagel缩合，形成两个乙烯连接的多环芳烃核心COFs，其显示出高结晶蜂窝结构，表面积高达1238 m2 g−1。由于多环芳烃构建块与乙烯的直接连接方式，所制备的COFs具有空间扩展的π-共轭和丰富的半导体性能。结果表明，它们具有优异的可见光催化活性和耐久性，在纯水中产生高达3820µmol g-1 h-1的H2O2，在苯甲醇作为空穴牺牲剂时甚至可以产生17080µmol g-1 h-1。
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-DMDP-2. (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.
Vinylene-Linking of Polycyclic Aromatic Hydrocarbons to π-Extended Two-Dimensional Covalent Organic Framework Photocatalyst for H2O2 Synthesis
https://doi.org/10.1002/anie.202418895
