Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States.
J Am Chem Soc. 2018 Jan 24;140(3):1116-1122. doi: 10.1021/jacs.7b11940. Epub 2018 Jan 16.
The electronic character of porphyrin active sites for electrocatalytic reduction of CO to CO in a two-dimensional covalent organic framework (COF) was tuned by modification of the reticular structure. Efficient charge transport along the COF backbone promotes electronic connectivity between remote functional groups and the active sites and enables the modulation of the catalytic properties of the system. A series of oriented thin films of these COFs was found to reduce CO to CO at low overpotential (550 mV) with high selectivity (faradaic efficiency of 87%) and at high current densities (65 mA/mg), a performance well beyond related molecular catalysts in regard to selectivity and efficiency. The catalysts are stable for more than 12 h without any loss in reactivity. X-ray absorption measurements on the cobalt L-edge for the modified COFs enable correlations between the inductive effects of the appended functionality and the electronic character of the reticulated molecular active sites.
通过对网状结构的修饰，调节了卟啉活性位的电子特性，用于在二维共价有机框架（COF）中电催化 CO 还原为 CO。沿 COF 主链的有效电荷输运促进了远程官能团与活性位之间的电子连接，并实现了对体系催化性能的调节。发现这些 COF 的一系列定向薄膜在低过电势（550 mV）下以高选择性（87%的法拉第效率）和高电流密度（65 mA/mg）将 CO 还原为 CO，在选择性和效率方面远远超过了相关的分子催化剂。催化剂在 12 小时以上的时间内保持稳定，没有任何反应性损失。对修饰后的 COF 的钴 L 边的 X 射线吸收测量使我们能够将附加官能团的感应效应与网状分子活性位的电子特性联系起来。
