Engineering Cu(I)/Cu(0) interfaces for efficient ethanol production from CO2 electroreduction

Summary

By leveraging a Cu(OH)F precursor, we construct a disk-like Cu(I)/Cu(0) interface model (P-Cu_x/Cu₂OF) composed of F-stabilized Cu(I) shell and Cu(0) core by one-step pulsed potential conversion. The interfacial region is shown to facilitate ethanol formation, guaranteeing a high FE(C₂₊) of up to 80.2%. Tuning the Cu(I)/Cu(0) ratio enhances the ethanol yield by 18.5-fold over pure P-Cu, with the corresponding partial current density (j_ethanol) reaching up to 128 mA/cm². This is enabled by a 3.6-fold boost in selectivity for the ethanol product (35.4%) and an overall 7.8-fold boost in activity (jC2+ up to 288 mA/cm²). The interactions between P-Cu and Cu₂OF upshift the d-band center of Cu sites on the interface region, which is critical to asymmetrical C-C coupling to form OCCOH∗, concurrent with a lowered energy barrier for ethanol formation. On the other hand, the ethylene-forming symmetrical C-C coupling occurs primarily on P-Cu away from the Cu(I)/Cu(0) interface.