Enhancing carbon enrichment by metal-organic cage to improve the electrocatalytic carbon dioxide reduction performance of silver-based catalyst.

Electrochemical reduction of carbon dioxide (CO2) into value-added chemicals provide an alternative technology for achieving carbon neutrality. Limited mass transfer of CO2 in aqueous electrolyte and unsatisfied catalytic activity are the major determinants that inhibit the CO2 conversion at industrial current density level. Herein, an electroreduction-generated metallic Ag atomic clusters supported on metal organic cage (Ag AC/MOC) electrocatalyst is reported to improve the enrichment of inorganic carbon species over catalytic sites for efficient CO2 electroreduction. In-situ infrared spectroscopy and density functional theory studies reveal that the Ag AC/MOC induces the CO2-concentrating in the metal organic cage via a spontaneous ionization of the accumulated CO2, which dramatically enhances the coverage of inorganic carbon species for accelerated kinetic of CO2 conversion. The highly dispersed Ag atomic clusters further reduce the activation energy of CO2 and promote the protonation of CO2 to form carboxyl species, enabling high selectivity toward CO. Hence, the Ag AC/MOC achieves a high CO faradaic efficiency of 97.0 %, while the highest CO partial current reaches 231.6 mA cm-2, which is significantly higher than that of metallic Ag electrocatalyst. This work demonstrates a deep insight into high-performance electrocatalyst design in view of CO2 transfer and catalytic activity.