本文要点：
无金属共价有机框架(COFs)因其独特的结构性质和显著的稳定性而成为氧还原反应(ORR)的有前途的催化剂。为了提高催化活性和选择性，已经研究了各种接头和连接物，以精确设计COFs。然而，COFs中顶点结构对ORR催化作用的影响仍未被充分探索。
这里，为了调节COF催化性能，作者通过引入不同的三嗪和噻吩单元来引入可调催化顶壁化学。催化顶壁方法允许对电子表面状态进行微调，从而改善中间吸附特性并加速ORR活性。
值得注意的是，工程COF实现了0.76 V的半波电位，超过了通过连接体或连接策略修饰的COFs。
理论计算表明，这种增强的活性源于OOH*中间体与噻吩顶点附近碳原子的强结合亲和力，促进OOH*还原成O2分子，这是ORR的限速步骤。
这些发现揭示了顶点壁工程在共轭COF框架中的关键作用，并为推进COFs设计以获得优异的ORR性能提供了重要的见解。
Figure 1. Design and synthesis of (a-c) TT-COFs via tunable vertex wall chemistry. Electrostatic potential mapped surface of (d-f) TT-COFs.
Figure 2. PXRD patterns of (a) TT-COF-1, (b) TT-COF-2, and (c) TT-COF-3. Unit cells of (d) TT-COF-1, (e) TT-COF-2, and (f) TT-COF-3. HR-TEM images of (g) TT-COF-1, (h) TT-COF-2, and (i) TT-COF-3. Scale bars: 20 nm. Insets: the corresponding FFT images.
Figure 3.(a) The electron absorption spectra, (b) Tauc plots, (c) Mott-Schottky curves, and (d) schematic energy band structure of TT-COFs.
Figure 4. (a) LSV curves, (b) Cdl Values, (c) Tafel slopes, (d) Electron-transfer number and the selectivity, (e) Limiting current density (jL) and kinetic current density (jK), (f) TOF values and mass activity, (g) Long-time stability and CH3OH-poison effect, of TT-COFs. (h) The onset and half-wave potential distributions of previously reported COF catalysts and TT-COF-3. (i) Radar plot showing a comparison of different electrochemical parameters to evaluate the oxygen reduction performance of the three TT-COFs.
Figure 5. (a-c) Optimized structures of TT-COF-1, TT-COF-2, and TT-COF-3 at the B3LYP/6–31G(d,p) level, (d) Schematic pathway for ORR on TT-COF-3, and (e) Free energy diagrams of ORR for TT-COF-1, TT-COF-2, and TT-COF-3.
Figure 6. Performance of zinc-air battery assembled with TT-COF-3. (a) Diagram of an aqueous rechargeable ZAB, (b) Open circuit voltage, (c) Power density curves and charge–discharge polarization, (d) Discharge curves at a constant current density of 20 mA cm−2, (e) Rate discharging– charging curves at various current densities, and (f) The durability stability test of the ZAB fabricated with TT-COF-3 measured at 5 mA cm−2.
https://doi.org/10.1002/anie.202500336
