Iodine-Modulated Silver Catalyst Reconstructed from a AgI Precatalyst for Efficient CO₂ Electroreduction to CO

Silver (Ag) is a promising catalyst for selective CO₂-to-CO conversion, yet its practical application is constrained by insufficient activity and limited stability. To address these issues, we have developed a halogen-retentive electrochemical reconstruction strategy to construct an iodine-modulated Ag catalyst (I-Ag) derived from a AgI precatalyst. This approach enables the direct incorporation of I ions into the Ag catalysts, creating a stable, I-retaining surface that modulates the electronic structure of Ag sites. The resulting I-Ag catalyst achieves a high CO Faradaic efficiency of 97.6% at -0.6 V versus RHE and maintains selectivity above 90% over 12 h of operation, demonstrating significantly enhanced activity and stability compared to commercial Ag. In situ FTIR spectroscopy and density functional theory calculations reveal that the electron-deficient Ag sites induced by I moderation facilitate the adsorption and stabilization of the key *COOH intermediate, thereby lowering the energy barrier for CO₂ reduction to CO. This work provides a practical reconstruction strategy and mechanistic insight into halogen-mediated catalyst design for efficient and durable CO₂ electroreduction.