Selective electroreduction of carbon dioxide to ethylene over stable iodide-induced asymmetric copper sites within a metal-organic polyhedron
Yaguang Peng, Yinlin Chen, Zi Wang, Yaoyu Yin, Jiangnan Li, Huanyan Liu, Jiapeng Jiao, Wenling Zhao, Ran Duan, Pei Zhang, Jiahao Yang, Hengan Wang, Xueqing Xing, Zhimin Liu, Sihai Yang⧫, Xinchen Kang, Buxing Han
Abstract
Porous Cu-based metal-organic compounds have attracted increasing attention for CO 2 electroreduction due to their well-defined porous structures and abundant metal sites. However, the classical {Cu 2 }-paddlewheel moieties within these materials often show poor electrochemical stability, leading to structural degradation during CO 2 electroreduction. Here, we report a strategy to generate stable {Cu(II)·Cu(I)} active sites by iodide species in a Cu-based metal-organic polyhedron, Cu-TCBB (TCBB=1,3,5-tris(4′-carboxybiphenyl-2-yl)benzene), to not only promote C 2 H 4 production but also clarify the real active sites of {Cu 2 }-paddlewheel-based materials during CO 2 electroreduction. Cu-TCBB exhibits a high Faradaic efficiency (FE) of 73.1% towards C 2 H 4 at −1.1 V vs. reversible hydrogen electrode (RHE) in 0.1 mol L −1 CsI aqueous solution, outperforming all porous metal-organic compounds to date. The presence of iodide-induced {Cu(II)·Cu(I)} sites was verified through in situ synchrotron X-ray diffraction and absorption spectroscopy, electron paramagnetic resonance spectroscopy, coupled with modelling, shedding light on the mechanism of CO 2 electroreduction over unique {Cu(II)·Cu(I)} sites.