Atomically Dispersed Cu Catalysts on Sulfide-Derived Defective Ag Nanowires for Electrochemical CO Reduction.

Single-atom catalysts (SACs) have shown potential for achieving an efficient electrochemical CO reduction reaction (CO2RR) despite challenges in their synthesis. Here, AgS/Ag nanowires provide initial anchoring sites for Cu SACs (Cu/AgS/Ag), then Cu/Ag(S) was synthesized by an electrochemical treatment resulting in complete sulfur removal, i.e., Cu SACs on a defective Ag surface. The CO2RR Faradaic efficiency (FE) of Cu/Ag(S) reaches 93.0% at a CO2RR partial current density () of 2.9 mA/cm under -1.0 V vs RHE, which outperforms sulfur-removed AgS/Ag without Cu SACs (Ag(S), 78.5% FE with 1.8 mA/cm). At -1.4 V vs RHE, both FE and over Cu/Ag(S) reached 78.6% and 6.1 mA/cm, which tripled those over Ag(S), respectively. As revealed by and characterizations together with theoretical calculations, the interacted Cu SACs and their neighboring defective Ag surface increase microstrain and downshift the d-band center of Cu/Ag(S), thus lowering the energy barrier by ∼0.5 eV for *CO formation, which accounts for the improved CO2RR activity and selectivity toward related products such as CO and C products.