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

Abstract

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.

Keywords: Ag atomic clusters; CO; CO(2) electrochemical reduction; Carbon enrichment; Metal–organic cage.