Construction of Low-Coordination Cu-C2 Single-Atoms Electrocatalyst Facilitating the Efficient Electrochemical CO2 Reduction to Methane.

Abstract

Constructing Cu single-atoms (SAs) catalysts is considered as one of the most effective strategies to enhance the performance of electrochemical reduction of CO2 (e-CO2 RR) towards CH4 , however there are challenges with activity, selectivity, and a cumbersome fabrication process. Herein, by virtue of the meta-position structure of alkynyl in 1,3,5-triethynylbenzene and the interaction between Cu and -C≡C-, a Cu SAs electrocatalyst (Cu-SAs/HGDY), containing low-coordination Cu-C2 active sites, was synthesized through a simple and efficient one-step method. Notably, this represents the first achievement of preparing Cu SAs catalysts with Cu-C2 coordination structure, which exhibited high CO2 -to-CH4 selectivity (72.1 %) with a high CH4 partial current density of 230.7 mA cm-2 , and a turnover frequency as high as 2756 h-1 , dramatically outperforming currently reported catalysts. Comprehensive experiments and calculations verified the low-coordination Cu-C2 structure not only endowed the Cu SAs center more positive electricity but also promoted the formation of H•, which contributed to the outstanding e-CO2 RR to CH4 electrocatalytic performance of Cu-SAs/HGDY. Our work provides a novel H⋅-transferring mechanism for e-CO2 RR to CH4 and offers a protocol for the preparation of two-coordinated Cu SAs catalysts.