Zhi Qianjun, Jiang Rong, Yang Xiya, Jin Yucheng, Qi Dongdong, Wang Kang, Liu Yunpeng, Jiang Jianzhuang
Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, Department of Chemistry and Chemical Engineering, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Science, Beijing, 100049, China.
Nat Commun. 2024 Jan 23;15(1):678. doi: 10.1038/s41467-024-44899-8.
Realization of stable and industrial-level HO electroproduction still faces great challenge due large partly to the easy decomposition of HO. Herein, a two-dimensional dithiine-linked phthalocyaninato cobalt (CoPc)-based covalent organic framework (COF), CoPc-S-COF, was afforded from the reaction of hexadecafluorophthalocyaninato cobalt (II) with 1,2,4,5-benzenetetrathiol. Introduction of the sulfur atoms with large atomic radius and two lone-pairs of electrons in the C-S-C linking unit leads to an undulated layered structure and an increased electron density of the Co center for CoPc-S-COF according to a series of experiments in combination with theoretical calculations. The former structural effect allows the exposition of more Co sites to enhance the COF catalytic performance, while the latter electronic effect activates the 2e oxygen reduction reaction (2e ORR) but deactivates the HO decomposition capability of the same Co center, as a total result enabling CoPc-S-COF to display good electrocatalytic HO production performance with a remarkable HO selectivity of >95% and a stable HO production with a concentration of 0.48 wt% under a high current density of 125 mA cm at an applied potential of ca. 0.67 V versus RHE for 20 h in a flow cell, representing the thus far reported best HO synthesis COFs electrocatalysts.
由于过氧化氢易于分解，实现稳定的工业级过氧化氢电合成仍然面临巨大挑战。在此，通过十六氟酞菁钴（II）与1,2,4,5-苯四硫醇反应制备了一种基于二维二硫代联苯酞菁钴（CoPc）的共价有机框架（COF），即CoPc-S-COF。结合一系列实验和理论计算，C-S-C连接单元中引入具有大原子半径和两对孤对电子的硫原子，导致CoPc-S-COF具有起伏的层状结构和Co中心电子密度增加。前一种结构效应使得更多的Co位点暴露出来，从而提高了COF的催化性能，而后一种电子效应激活了2e氧还原反应（2e ORR），但使同一Co中心的过氧化氢分解能力失活，总体结果是使CoPc-S-COF表现出良好的电催化过氧化氢生成性能，在流动池中，在约0.67 V（相对于RHE）的外加电位下，在125 mA cm的高电流密度下，过氧化氢选择性显著>95%，过氧化氢生成稳定，浓度为0.48 wt%，持续20 h，这代表了迄今为止报道的最佳过氧化氢合成COF电催化剂。
