Guo Hui, Si Duan-Hui, Zhu Hong-Jing, Chen Zi-Ao, Cao Rong, Huang Yuan-Biao
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 350002, Fujian, Fuzhou, P. R. China.
University of Chinese Academy of Sciences, 100049, Beijing, P. R. China.
Angew Chem Int Ed Engl. 2024 Apr 2;63(14):e202319472. doi: 10.1002/anie.202319472. Epub 2024 Feb 22.
Herein, we propose an oxygen-containing species coordination strategy to boost CO electroreduction in the presence of O. A two-dimensional (2D) conjugated metal-covalent organic framework (MCOF), denoted as NiPc-Salen(Co)-COF that is composed of the Ni-phthalocyanine (NiPc) unit with well-defined Ni-N-O sites and the salen(Co) moiety with binuclear Co-NO sites, is developed and synthesized for enhancing the CORR under aerobic condition. In the presence of O, one of the Co sites in the NiPc-Salen(Co)-COF that coordinated with the intermediate of *OOH from ORR could decrease the energy barrier of the activation of CO molecules and stabilize the key intermediate *COOH of the CORR over the adjacent Co center. Besides, the oxygen species axially coordinated Ni-N-O sites can favor in reducing the energy barrier of the intermediate *COOH formation for the CORR. Thus, NiPc-Salen(Co)-COF exhibits high oxygen-tolerant CORR performance and achieves outstanding CO Faradaic efficiency (FE) of 97.2 % at -1.0 V vs. the reversible hydrogen electrode (RHE) and a high CO partial current density of 40.3 mA cm at -1.1 V in the presence of 0.5 % O, which is superior to that in pure CO feed gas (FE=94.8 %, j=19.9 mA cm). Notably, the NiPc-Salen(Co)-COF achieves an industrial-level current density of 128.3 mA cm in the flow-cell reactor with 0.5 % O at -0.8 V, which is higher than that in pure CO atmosphere (j=104.8 mA cm). It is worth noting that an excellent FE of 86.8 % is still achieved in the presence of 5 % O at -1.0 V. This work provides an effective strategy to enable the CORR under O atmosphere by utilizing the *OOH intermediates of ORR to boost CO electroreduction.
在此，我们提出一种含氧物种配位策略，以在有氧存在的情况下促进CO电还原。开发并合成了一种二维（2D）共轭金属共价有机框架（MCOF），记为NiPc-Salen(Co)-COF，它由具有明确Ni-N-O位点的镍酞菁（NiPc）单元和具有双核Co-NO位点的salen(Co)部分组成，用于在有氧条件下增强CO电还原反应（CORR）。在有氧存在的情况下，NiPc-Salen(Co)-COF中与氧还原反应（ORR）的OOH中间体配位的一个Co位点可以降低CO分子活化的能垒，并在相邻的Co中心上稳定CORR的关键中间体COOH。此外，轴向配位的氧物种Ni-N-O位点有利于降低CORR中间体COOH形成的能垒。因此，NiPc-Salen(Co)-COF表现出高的耐氧CORR性能，在相对于可逆氢电极（RHE）为-1.0 V时，在0.5% O存在下实现了97.2%的出色CO法拉第效率（FE）和-1.1 V时40.3 mA cm的高CO分电流密度，优于纯CO进料气中的性能（FE = 94.8%，j = 19.9 mA cm）。值得注意的是，NiPc-Salen(Co)-COF在-0.8 V、含0.5% O的流动池反应器中实现了128.3 mA cm的工业级电流密度，高于纯CO气氛中的电流密度（j = 104.8 mA cm）。值得注意的是，在-1.0 V、5% O存在的情况下仍实现了86.8%的出色FE。这项工作提供了一种有效的策略，通过利用ORR的OOH中间体在O气氛下实现CORR，以促进CO电还原。
