Cage-Confined Cu Clusters Boost Carbon Dioxide Electroreduction into Methane.

Zhu, Jiangchen; Yang, Zhengwu; Xu, Zifan; Zheng, Han; Fan, Ming-Hui; Zhao, Zhi; Kong, Xiangdong; Geng, Zhigang · Nano Lett · 2025

basic_science · Level V

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Abstract

The microgeometric structures of Cu play important roles in regulating the catalytic selectivity of CO<sub>2</sub> electroreduction. Herein, we fabricated sub-nanometer Cu clusters confined in a metal organic framework (UIO-66-NDC) with certain tetrahedral/octahedral cages for efficient methane (CH<sub>4</sub>) synthesis. During CO<sub>2</sub> electroreduction, Cu clusters confined in UIO-66-NDC exhibited a faradaic efficiency for CH<sub>4</sub> as high as 72.0% and a partial current density of -361.0 mA cm<sup>-2</sup>. Based on <i>in situ</i> characterizations, we revealed that Cu clusters with a coordination number of around 7 were <i>in situ</i> generated in the octahedral cages of UIO-66-NDC during electrolysis. <i>In situ</i> spectroscopy measurements unraveled that *CO with bridge adsorption (*CO<sub>bridge</sub>) was favorable to be adsorbed on the surface of Cu clusters. Theoretical calculations suggested that *CO<sub>bridge</sub> was more inclined to be protonated into *CHO and then into *CH<sub>2</sub>O rather than going through the C-C coupling path on Cu clusters, thus boosting CH<sub>4</sub> selectivity.