Regulated Cu Diatomic Distance Promoting Carbon-Carbon Coupling During CO₂ Electroreduction

To address the bottle-neck carbon-carbon coupling issue during electrochemical carbon dioxide reduction (eCO₂RR) to multicarbon (C₂₊) products, this work develops an anion-directed strategy (Cl^-, NO₃ ^-, and SO₄ ^2-) to regulate interatomic distance of Cu diatoms. In comparison to pristine Cu (with a typical Cu-Cu distance of 2.53 Å), Cu-boroimidazole frameworks (BIF)/SO₄, NO₃, and Cl material shows elongated diatomic distance of 3.90 Å, 4.21 Å, and 3.30 Å, respectively. Among them, the Cu-BIF/Cl exhibits an outstanding eCO₂RR performance with a Faradaic efficiency of 72.12% for C₂₊ products and an industrial-level current density of 539.0 mA cm^-2 at -1.75 V versus RHE. Significantly, according to theoretical and in situ experimental investigation, the highly electronegative Cl^- ion lifts d-band center of Cu sites of Cu-BIF/Cl, facilitating *CO adsorption with a low Gibbs free energy and its later dimerization overcoming a small energy barrier. In addition, this strategy to manipulate interatomic distance for diatomic catalysts, can also be adaptable to other reactions involving intermediate coupling and following the Langmuir-Hinshelwood mechanism, such as carbon-nitrogen coupling, nitrogen-nitrogen coupling, etc.