In Situ Synthesis\nof Copper-Based Metal–Organic\nFrameworks with Ligand Defects for Electrochemical Reduction of CO<sub>2</sub> into C<sub>2</sub> Products

Electrochemical reduction of CO<sub>2</sub> into high-value-added\nproducts is a potential approach to solving environmental problems\nbut is limited by poor product selectivity and low efficiency. Metal–organic\nframework (MOF) materials have been considered one of the most promising\ncatalysts, but their application is limited by complicated preparation\nprocesses, especially during the synthesis of organic ligands. In\nthis work, a new three-dimensional Cu-MOF (<b>JXUST-301</b>)\nwith high porosity was constructed based on the naphthalene diimide\n(NDI) ligand. Furthermore, <b>JXUST-301</b> with ligand defects\n(<b>JXUST-301D</b>) originating from the missing NDI unit was\nsynthesized via an <i>in situ</i> reaction. The presence\nof ligand defects endows <b>JXUST-301D</b> with a better CO<sub>2</sub>RR performance with a FE<sub>C2</sub> of 56.7% and a <i>j</i><sub>C2</sub> of −162.4 mA cm<sup>–2</sup>. Mechanistic studies revealed that the hierarchical pore structure\nand amino sites are created from the absence of the NDI unit, which\npromotes the exposure of catalytically active sites and CO<sub>2</sub> enrichment. Furthermore, the electronic structure of the Cu sites\nis modulated to upshift the d-band center, facilitating chemical adsorption\nand activation of key reaction intermediates. This work provides new\ninsight into the <i>in situ</i> preparation of efficient\nCu-MOF catalysts by introducing defects for the CO<sub>2</sub>RR.