A novel Cu-based covalent organic framework with Cu-N2O2 single sites for efficient CO2 electroreduction to methane
Wenli Su, Shuxin Zhong, Yu Fan
Abstract
Single-site catalysts (SSCs) are useful for CO 2 electroreduction (CO 2 ER) to methane (CH 4 ), but their selectivities for CH 4 are still unsatisfactory due to the lack of efficient active sites. Herein, a novel Cu-based covalent organic framework (CuN 2 O 2 -COF) with Cu-N 2 O 2 single sites was synthesized by the Schiff base reaction and used in CO 2 ER to improve CH 4 generation for the first time. Compared with typical SSCs containing Cu-N 4 or Cu-O 4 sites, CuN 2 O 2 -COF exhibited superior CH 4 production efficiency in CO 2 ER: the Faradaic efficiency of CH 4 was as high as 85.4%, and the CH 4 partial current density reached 313 mA·cm −2 at −1.3 V, which exceeded those of most electrocatalysts reported thus far. Theoretical calculations indicated that compared with the Cu-N 4 or Cu-O 4 sites in typical SSCs, the new Cu-N 2 O 2 configuration in CuN 2 O 2 -COF increased the d‐band center of the Cu sites and enhanced the adsorption of key intermediates (*COOH and *CHO) required for CO 2 ER to CH 4 .