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

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-CO₂RR) 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-CO₂RR to CH₄ electrocatalytic performance of Cu−SAs/HGDY. Our work provides a novel H⋅-transferring mechanism for e-CO₂RR to CH₄ and offers a protocol for the preparation of two-coordinated Cu SAs catalysts.