Enhanced Intermediates Inter-migration on Ag Single-Atom Alloys for Boosting Multicarbon Product Selectivity in CO₂ Electroreduction

Electrochemical CO₂ reduction reaction (CO₂RR) to multicarbon (C₂₊) products holds immense significance in promoting a closed carbon cycle and solving global energy problems, but it faces challenges of unsatisfactory selectivity. In this work, we constructed an Ag single-atom alloy cascade catalyst (AgCu-SAA) using an epoxide gelation approach, which enhanced the utilization efficiency of the CO intermediate through an inter-migration pathway. As a result, the C₂₊ products' Faradaic efficiency (FE) of 83.4% was achieved at a current density of 900 mA cm^-2. Moreover, the FE of the C₂₊ products remained as high as 74.8% even at a high current density of 1100 mA cm^-2. In situ Raman spectra and density functional theory (DFT) calculations reveal that CO₂ is first converted to CO over the single-atom Ag site. Subsequently, the generated CO is directly transferred to the adjacent Cu site rather than desorbing into the electrolyte. This process avoids the inefficient migration of CO inter-mediates, thereby enhancing the selectivity for the formation of C₂₊ products.