Anion Modulation of Ag‐Imidazole Cuboctahedral Cage Microenvironments for Efficient Electrocatalytic CO<sub>2</sub> Reduction
Wenqian Yang, Qijie Mo, Qi‐Ting He, Xiangping Li, Ziqian Xue, Yu‐Lin Lu, Jie Chen, Kai Zheng, Yanan Fan, Guangqin Li, Cheng‐Yong Su, Cheng‐Yong Su
Abstract
Abstract How to achieve CO 2 electroreduction in high efficiency is a current challenge with the mechanism not well understood yet. The metal‐organic cages with multiple metal sites, tunable active centers, and well‐defined microenvironments may provide a promising catalyst model. Here, we report self‐assembly of Ag 4 L 4 type cuboctahedral cages from coordination dynamic Ag + ion and triangular imidazolyl ligand 1,3,5‐tris(1‐benzylbenzimidazol‐2‐yl) benzene (Ag‐MOC‐X, X=NO 3 , ClO 4 , BF 4 ) via anion template effect. Notably, Ag‐MOC‐NO 3 achieves the highest CO faradaic efficiency in pH‐universal electrolytes of 86.1 % (acidic), 94.1 % (neutral) and 95.3 % (alkaline), much higher than those of Ag‐MOC‐ClO 4 and Ag‐MOC‐BF 4 with just different counter anions. In situ attenuated total reflection Fourier transform infrared spectroscopy observes formation of vital intermediate *COOH for CO 2 ‐to‐CO conversion. The density functional theory calculations suggest that the adsorption of CO 2 on unsaturated Ag‐site is stabilized by C−H⋅⋅⋅O hydrogen‐bonding of CO 2 in a microenvironment surrounded by three benzimidazole rings, and the activation of CO 2 is dependent on the coordination dynamics of Ag‐centers modulated by the hosted anions through Ag⋅⋅⋅X interactions. This work offers a supramolecular electrocatalytic strategy based on Ag‐coordination geometry and host–guest interaction regulation of MOCs as high‐efficient electrocatalysts for CO 2 reduction to CO which is a key intermediate in chemical industry process.