Wu Qiu-Jin, Si Duan-Hui, Ye Shihua, Dong Yu-Liang, Cao Rong, Huang Yuan-Biao
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fujian, Fuzhou 350002, People's Republic of China.
University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China.
J Am Chem Soc. 2023 Sep 13;145(36):19856-19865. doi: 10.1021/jacs.3c06113. Epub 2023 Aug 31.
Introducing an external visible-light field would be a promising strategy to improve the activity of the electrocatalytic CO reduction reaction (CORR), but it still remains a challenge due to the short excited-state lifetime of active sites. Herein, Ru(bpy)Cl struts as powerful photosensitive donors were immobilized into the backbones of Co-porphyrin-based covalent organic frameworks (named Co-Bpy-COF-Ru, is the molar ratio of Ru and Co species, = 1/2 and 2/3) via coordination bonds, for the photo-coupled CORR to produce CO. The optimal Co-Bpy-COF-Ru displays a high CO Faradaic efficiency of 96.7% at -0.7 V vs reversible hydrogen electrode (RHE) and a CO partial current density of 16.27 mA cm at -1.1 V vs RHE under the assistance of light, both of which were far surpassing the values observed in the dark. The significantly enhanced activity is mainly attributed to the incorporation of a Ru(bpy)Cl donor with long excited-state lifetime and concomitantly giant built-in electric field in Co-Bpy-COF-Ru, which efficiently accelerate the photo-induced electron transfer from Ru(bpy)Cl to the cobalt-porphyrin under the external light. Thus, the cobalt-porphyrin active sites have a longer excited-state lifetime to lower the rate-determining steps' energy occurring during the actual photo-coupled electrocatalytic CORR process. This is the first work of porphyrin-based COFs for photo-coupled CORR, opening a new frontier for the construction of efficient photo-coupled electrocatalysts.
引入外部可见光场可能是提高电催化CO还原反应（CORR）活性的一种有前景的策略，但由于活性位点的激发态寿命较短，这仍然是一个挑战。在此，作为强大光敏供体的Ru(bpy)Cl支柱通过配位键固定在钴卟啉基共价有机框架（命名为Co-Bpy-COF-Ru， 为Ru和Co物种的摩尔比， = 1/2和2/3）的骨架中，用于光耦合CORR以产生CO。在光照辅助下，最佳的Co-Bpy-COF-Ru在相对于可逆氢电极（RHE）为-0.7 V时显示出96.7%的高CO法拉第效率，在相对于RHE为-1.1 V时显示出16.27 mA cm的CO分电流密度，这两个值都远远超过在黑暗中观察到的值。活性的显著增强主要归因于掺入了具有长激发态寿命的Ru(bpy)Cl供体以及Co-Bpy-COF-Ru中伴随的巨大内建电场，这在外部光的作用下有效地加速了光诱导电子从Ru(bpy)Cl转移到钴卟啉。因此，钴卟啉活性位点具有更长的激发态寿命，以降低实际光耦合电催化CORR过程中发生的速率决定步骤的能量。这是基于卟啉的COF用于光耦合CORR的第一项工作，为构建高效的光耦合电催化剂开辟了新的前沿。
