Song Yun, Guo Peng, Ma Tinghao, Su Jianjun, Huang Libei, Guo Weihua, Liu Yong, Li Geng, Xin Yinger, Zhang Qiang, Zhang Siwei, Shen Hanchen, Feng Xing, Yang Dengtao, Tian Jia, Ravi Sai Kishore, Tang Ben Zhong, Ye Ruquan
Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, 999077, China.
City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518057, China.
Adv Mater. 2024 Apr;36(17):e2310037. doi: 10.1002/adma.202310037. Epub 2023 Dec 6.
Metalloporphyrins and metallophthalocyanines emerge as popular building blocks to develop covalent organic nanosheets (CONs) for CO reduction reaction (CORR). However, existing CONs predominantly yield CO, posing a challenge in achieving efficient methanol production through multielectron reduction. Here, ultrathin, cationic, and cobalt-phthalocyanine-based CONs (iminium-CONs) are reported for electrochemical CO-to-CHOH conversion. The integration of quaternary iminium groups enables the formation of ultrathin morphology with uniformly anchored cobalt active sites, which are pivotal for facilitating rapid multielectron transfer. Moreover, the cationic iminium-CONs exhibit a lower activity for hydrogen evolution side reaction. Consequently, iminium-CONs manifest significantly enhanced selectivity for methanol production, as evidenced by a remarkable 711% and 270% improvement in methanol partial current density (j) compared to pristine CoTAPc and neutral imine-CONs, respectively. Under optimized conditions, iminium-CONs deliver a high j of 91.7 mA cm at -0.78 V in a flow cell. Further, iminium-CONs achieve a global methanol Faradaic efficiency (FE) of 54% in a tandem device. Thanks to the single-site feature, the methanol is produced without the concurrent generation of other liquid byproducts. This work underscores the potential of cationic covalent organic nanosheets as a compelling platform for electrochemical six-electron reduction of CO to methanol.
金属卟啉和金属酞菁成为开发用于CO还原反应（CORR）的共价有机纳米片（CONs）的常用构建块。然而，现有的CONs主要生成CO，这对通过多电子还原实现高效甲醇生产构成了挑战。在此，报道了用于电化学CO到CHOH转化的超薄、阳离子型和基于钴酞菁的CONs（亚胺基-CONs）。季铵亚胺基团的整合使得能够形成具有均匀锚定钴活性位点的超薄形态，这对于促进快速多电子转移至关重要。此外，阳离子亚胺基-CONs对析氢副反应表现出较低的活性。因此，亚胺基-CONs对甲醇生产表现出显著提高的选择性，与原始CoTAPc和中性亚胺-CONs相比，甲醇分电流密度（j）分别显著提高了711%和270%。在优化条件下，亚胺基-CONs在流动池中于-0.78 V时提供91.7 mA cm的高j。此外，亚胺基-CONs在串联装置中实现了54%的全球甲醇法拉第效率（FE）。由于单中心特性，甲醇的产生没有同时生成其他液体副产物。这项工作强调了阳离子共价有机纳米片作为将CO电化学六电子还原为甲醇的有吸引力平台的潜力。
