Zhao Zhen-Hua, Huang Jia-Run, Liao Pei-Qin, Chen Xiao-Ming
MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, GBRCE for Functional Molecular Engineering, School of Chemistry, IGCME, Sun Yat-Sen University, Guangzhou 510275, China.
Chemistry and Chemical Engineering Guangdong Laboratory, Shantou 515031, China.
J Am Chem Soc. 2023 Dec 13;145(49):26783-26790. doi: 10.1021/jacs.3c08974. Epub 2023 Nov 28.
The electroreduction of CO into value-added liquid fuels holds great promise for addressing global environmental and energy challenges. However, achieving highly selective yielding of multi-carbon oxygenates through the electrochemical CO reduction reaction (eCORR) is a formidable task, primarily due to the sluggish asymmetric C-C coupling reaction. In this study, a novel metal-organic framework () with unprecedented heterometallic Sn···Cu dual sites (namely, a pair of SnNO and CuN sites bridged by -N atoms) was designed to overcome this limitation. demonstrated an impressive Faradic efficiency (FE) of 56(2)% for eCORR to alcohols, achieving a current density of 68 mA cm at a low potential of -0.57 V (vs RHE). Notably, no significant degradation was observed over a continuous 35 h operation at the specified current density. Mechanistic investigations revealed that, in comparison to the copper site, the SnNO site exhibits a higher affinity for oxygen atoms. This enhanced affinity plays a pivotal role in facilitating the generation of the key intermediate *OCH. Consequently, compared to homometallic Cu···Cu dual sites (generally yielding ethylene product), the heterometallic dual sites were proved to be more thermodynamically favorable for the asymmetric C-C coupling between *CO and *OCH, leading to the formation of the key intermediate *CO-*OCH, which is favorable for yielding ethanol product.
将CO电还原为高附加值液体燃料在应对全球环境和能源挑战方面具有巨大潜力。然而，通过电化学CO还原反应（eCORR）实现多碳含氧化合物的高选择性生成是一项艰巨的任务，主要原因是不对称C-C偶联反应缓慢。在本研究中，设计了一种具有前所未有的异金属Sn···Cu双位点（即由-N原子桥接的一对SnNO和CuN位点）的新型金属有机框架，以克服这一限制。该框架在eCORR生成醇类反应中表现出令人印象深刻的56(2)%的法拉第效率（FE），在-0.57 V（相对于可逆氢电极）的低电位下实现了68 mA cm的电流密度。值得注意的是，在指定电流密度下连续运行35小时未观察到明显降解。机理研究表明，与铜位点相比，SnNO位点对氧原子具有更高的亲和力。这种增强的亲和力在促进关键中间体OCH的生成中起关键作用。因此，与同金属Cu···Cu双位点（通常生成乙烯产物）相比，异金属双位点被证明在热力学上更有利于CO和OCH之间的不对称C-C偶联，导致关键中间体CO-*OCH的形成，这有利于生成乙醇产物。
