Yang Shuai, Bi Shuai, Zhai Lipeng, Xu Qing
CAS Key Laboratory of Low-Carbon Conversion Science and Engineering, Shanghai Advanced Research Institute, Chinese Academy of Sciences Shanghai 201210 P. R. China
Department of Chemistry, City University of Hong Kong Kowloon Hong Kong 999077 P. R. China.
Chem Sci. 2025 Jul 21. doi: 10.1039/d5sc02151k.
Two-dimensional (2D) covalent organic frameworks (COFs) with metal centers are ideal templates to construct electrocatalysts due to their high degree of structural controllability. However, the metal centers are stacked in columns with limited space, which impedes the mass delivered to catalytic sites across the pore channels. Herein, we demonstrate a topologic synthesis strategy for constructing catalytic sites in three-dimensional (3D) space. The designed 3D COF adopts an topology, with a large space of 1.15 and 1.53 nm between the metal sites along the parallel and vertical directions, respectively. spectroscopy revealed that ∼100% Ni-N sites in 3D frameworks were reconstructed to Ni-N-NO, while the reconstruction proportion of Ni-N sites was ∼40% for 2D COF (with a distance of 0.38 nm between metal sites). The catalytic 3D COFs enable the electrochemical synthesis of NH the reduction of nitrate (NORR) at a rate of 9.51 mg mg h, corresponding to 140% of that for the 2D COF at -0.7 V RHE. Theoretical calculations further revealed that the reconstructed Ni-N-NO site had a stronger binding ability of the reactants and intermediates than that of the initial Ni-N site and thus contributed to higher activity. This work provides general design strategies for heterogeneous catalysts in electrocatalytic systems.
具有金属中心的二维（2D）共价有机框架（COF）因其高度的结构可控性而成为构建电催化剂的理想模板。然而，金属中心以有限的空间堆积成列，这阻碍了物质通过孔道输送到催化位点。在此，我们展示了一种在三维（3D）空间中构建催化位点的拓扑合成策略。设计的3D COF采用了一种拓扑结构，沿平行和垂直方向金属位点之间的空间分别为1.15和1.53 nm。光谱学表明，3D框架中约100%的Ni-N位点重构为Ni-N-NO，而2D COF（金属位点之间的距离为0.38 nm）中Ni-N位点的重构比例约为40%。催化性3D COF能够以9.51 mg mg h的速率电化学合成NH，即硝酸盐还原反应（NORR），在-0.7 V（相对于可逆氢电极，RHE）时相当于2D COF的140%。理论计算进一步表明，重构的Ni-N-NO位点对反应物和中间体的结合能力比初始的Ni-N位点更强，因此具有更高的活性。这项工作为电催化系统中的多相催化剂提供了通用的设计策略。
