Electrocatalytic CO 2 Reduction in Acidic Media via Host‐Guest Synergy Engineered Ionic Liquid@Metal‐Covalent Organic Framework

Although acidic CO 2 electroreduction to multicarbon products offers superior carbon utilization compared to alkaline/neutral routes, its performance is severely hampered by proton‐enrichment‐induced hydrogen evolution (HER). To address this issue, we propose a host‐guest cooperative catalysis strategy by constructing a structurally well‐defined Ionic Liquid functionalized Metal‐covalent organic framework (IL@MCOF). Within this architecture, the confined ionic liquid creates a localized high‐concentration CO 2 microenvironment and induces interfacial water restructuring, thereby effectively suppressing HER caused by proton enrichment. Meanwhile, non‐covalent interactions between the π‐conjugated framework of MCOF and the IL cations promote directional transport of adsorbed CO 2 toward copper active sites. Mechanistic studies further reveal that the MCOF catalytic sites synergize with the guest IL to lower the formation energy barriers of the key C 2+ intermediates *COCO and *OCCOH. Consequently, IL@MCOF achieves a record 56.5% Faradaic efficiency with −162 mA cm −2 for C 2+ products at −1.8 V versus RHE in acidic media, surpassing all reported MOF‐based acidic catalysts. This work provides a host‐guest molecular engineering approach for highly selective acidic CO 2 electroreduction.