Sn‐Ag Synergistic Effect Enhances High‐Rate Electrocatalytic CO₂‐to‐Formate Conversion on Porous Poly(Ionic Liquid) Support

Abstract The electrocatalytic transformation of carbon dioxide (CO 2 ) to formate is a promising route for highly efficient conversion and utilization of CO 2 gas, due to the low production cost and the ease of storage of formate. In this work, porous poly(ionic liquid) (PPIL)‐based tin‐silver (Sn‐Ag) bimetallic hybrids (PPIL m ‐Sn x Ag 10‐ x ) are prepared for high‐performance formate electrolytic generation. Under optimal conditions, an excellent formate Faradaic efficiency of 95.5% with a high partial current density of 214.9 mA cm −2 is obtained at −1.03 V (vs reversible hydrogen electrode). Meanwhile, the high selectivity of formate (>≈83%) is maintained in a wide potential range (>630 mV). Mechanistic studies demonstrate that the presence of Ag‐species is vital for the formation, maintenance, and high dispersion of tetravalent Sn(IV)‐species, which accounts for the active sites for CO 2 ‐to‐formate conversion. Further, the introduction of Ag‐species significantly enhances the activity by increasing the electron density near the Fermi energy level.