Asymmetric Cu−N₁O₃ Sites Coupling Atop‐type and Bridge‐type Adsorbed *C₁ for Electrocatalytic CO₂‐to‐C₂ Conversion

Abstract

2D functional porous frameworks offer a platform for studying the structure‐activity relationships during electrocatalytic CO2 reduction reaction (CO2RR). Yet challenges still exist to breakthrough key limitations on site configuration (typical M–O4 or M–N4 units) and product selectivity (common CO2‐to‐CO conversion). Herein, a novel 2D metal‐organic framework (MOF) with planar asymmetric N/O mixed coordinated Cu–N1O3 unit is constructed, labeled as BIT‐119. When applied to CO2RR, BIT‐119 could reach a CO2‐to‐C2 conversion with C2 partial current density ranging from 36.9 to 165.0 mA cm−2 in flow cell. Compared to the typical symmetric Cu–O4 units, asymmetric Cu–N1O3 units lead to the re‐distribution of local electron structure, regulating the adsorption strength of several key adsorbates and the following catalytic selectivity. From experimental and theoretical analyses, Cu−N1O3 sites could simultaneously couple the atop‐type (on Cu site) and bridge‐type (on Cu–N site) adsorption of *C1 species to reach the CO2‐to‐C2 conversion. This work broadens the feasible C−C coupling mechanism on 2D functional porous frameworks.