Regulation of the <i>D</i> ‐Band Center Through Ligand Engineering in Silver Cluster‐Based MOFs Enhances Acidic CO ₂ Electroreduction

Abstract

Abstract Acidic electrochemical CO 2 reduction reaction (eCO 2 RR) offers a promising way for achieving high CO 2 utilization efficiency and circumventing carbonate deposition issues. However, it is plagued by a compromised catalytic performance due to the severe hydrogen evolution reaction (HER). Here, two types of silver chalcogenolate cluster‐based MOFs were synthesized through ligand engineering by anchoring Ag 12 clusters with tri‐topic imidazole and pyridyl ligands respectively. The imidazole‐based MOF Ag 12 THIT demonstrated outstanding performance for the electroreduction of CO 2 to CO. In acidic electrolyte of pH ≈ 2, it achieved a Faradaic efficiency (FE) of 98.5% with a commercial current density of 328.0 mA cm −2 at − 1.6 V versus RHE. Moreover, the CO partial current density ( j CO ) reached a maximum of 447.2 mA cm −2 with a FE CO of 96.8% at − 1.7 V versus RHE. No obvious degradation was observed during 70 h of continuous operation, and the performance significantly outperformed those of pyridyl‐based MOFs Ag 12 TPEB and Ag 12 TPMA . Mechanistic studies revealed that the imidazole ligand endows Ag 12 THIT with enhanced Lewis basicity and superior σ ‐donating ability, thereby strengthening the ligand field with an upshifted d ‐band center and reduced energy barriers. This ligand effect facilitates more efficient electron transfer to *COOH intermediates, thus promoting acidic CO 2 to CO conversion.