Copper–Carbon Bond Metal–Organic Frameworks for Highly Efficient and Stable CO2 Electrochemical Methanation

Cu-based metal-organic frameworks (Cu-MOFs) integrate the high tunability of molecular systems with the high activity of metal sites, making them promising electrocatalysts for the electrocatalytic reduction of carbon dioxide (CO2RR). To date, the primary challenge in the application of Cu-MOFs in electrocatalytic CO2RR is their poor stability during the reduction process. Herein, we pursue experimental and theoretical insights into Cu-C MOFs for the CO2RR for the first time. Notably, Cu-TEPT, a Cu-C MOF synthesized through the reaction of tetrakis(acetonitrile)copper(I) Trifluoromethanesulfonate with 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine (TEPT) ligand, exhibited remarkable activity toward methane (CH4) production. It achieved a high Faradaic efficiency (FE) of 83.6% and a CH4 partial current density of up to 295.4 mA cm-2, marking one of the highest performances reported to date. Experimental and theoretical studies indicated that the outstanding CO2RR performance and stability of Cu-TEPT result from the ligand-protected alkynyl Cu(I) sites in Cu-TEPT, which effectively stabilize the Cu+ sites and accelerate the kinetics of CO2 to CH4.