Atomically Thin, Ionic-Covalent Organic Nanosheets for Stable, High-Performance Carbon Dioxide Electroreduction

作者：Song, Yun; Zhang, Jun-Jie; Dou, Yubing; Zhu, Zhaohua; Su, Jianjun; Huang, Libei; Guo, Weihua; Cao, Xiaohu; Cheng, Le; Zhu, Zonglong; Zhang, Zhenhua; Zhong, Xiaoyan; Yang, Dengtao^*; Wang, Zhaoyu; Tang, Ben Zhong; Yakobson, Boris, I^*; Ye, Ruquan^*

来源：Advanced Materials, 2022, 34(42): 2110496.

DOI：10.1002/adma.202110496

• carbon dioxide reduction
• covalent organic frameworks
• ionic nanosheets
• positive charge
• ultrathin materials

The incorporation of charged functional groups is effective to modulate the activity of molecular complexes for the CO2 reduction reaction (CO2RR), yet long-term heterogeneous electrolysis is often hampered by catalyst leaching. Herein, an electrocatalyst of atomically thin, cobalt-porphyrin-based, ionic-covalent organic nanosheets (CoTAP-iCONs) is synthesized via a post-synthetic modification strategy for high-performance CO2-to-CO conversion. The cationic quaternary ammonium groups not only enable the formation of monolayer nanosheets due to steric hindrance and electrostatic repulsion, but also facilitate the formation of a *COOH intermediate, as suggested by theoretical calculations. Consequently, CoTAP-iCONs exhibit higher CO2RR activity than other cobalt-porphyrin-based structures: an 870% and 480% improvement of CO current densities compared to the monomer and neutral nanosheets, respectively. Additionally, the iCONs structure can accommodate the cationic moieties. In a flow cell, CoTAP-iCONs attain a very small onset overpotential of 40 mV and a stable total current density of 212 mA cm(-2) with CO Faradaic efficiency of >95% at -0.6 V for 11 h. Further coupling the flow electrolyzer with commercial solar cells yields a solar-to-CO conversion efficiency of 13.89%. This work indicates that atom-thin, ionic nanosheets represent a promising structure for achieving both tailored activity and high stability.

• 单位
  西北工业大学