Rational Ligand‐Mediated Microenvironment Regulation in Trinuclear Cu‐Based Metal‐Covalent Organic Frameworks for Enhanced Electrocatalytic CO Reduction

Electrochemical CO reduction (eCORR) is a promising route to high‐value multicarbon products, yet its performance is fundamentally constrained by two intrinsic bottlenecks: insufficient CO surface coverage and sluggish C─C coupling kinetics. Herein, via a ligand engineering strategy, we construct synergistic centers for in‐situ CO enrichment and conversion by conducting Schiff‐base condensation between trinuclear cuprous clusters and organic units featuring sp 2 ‐hybridized nitrogen centers, successfully synthesizing Cu(I)‐based two‐dimensional metal‐covalent organic frameworks (Cu‐TAPA). At a current density of 100 mA cm −2 , Cu‐TAPA achieves a Faradaic efficiency of 81.28% toward C 2 products, representing state‐of‐the‐art performance. Experimental and theoretical investigations collectively demonstrate that the polar nitrogen sites of TAPA ligands pre‐enrich CO molecules through electrostatic interactions, creating a microenvironment with a high local CO concentration; the enriched CO is subsequently transferred to copper catalytic sites, substantially lowering the C─C coupling energy barrier and thereby enhancing C 2 selectivity. This study proposes, at the atomic level, a new paradigm of ligand‐mediated “in‐situ CO enrichment‐conversion” for catalyst design, providing a general strategy for the precise construction of efficient eCORR catalysts.