Twin-Boundary Cu₂-Pair Pockets Drive Spatial Proximity of Key Intermediates for Efficient Urea Electrosynthesis

Electrocatalytic urea synthesis from carbon dioxide (CO₂) and nitrate (NO₃ ^-) offers an alternative to the energy-intensive Bosch-Meiser process but is limited by poor selectivity and Faradaic efficiency (FE). Herein, we proposed a defect engineering strategy by constructing ordered Cu nanowire electrocatalysts enriched with abundant twin boundaries (TBs) that can drive spatial proximity between the key intermediates derived from asymmetric activation of CO₂ and optimized adsorption of NO₃ ^-. Specifically, it could achieve a high FE of 61.81% and a peak yield rate of 5.80 mg h^-1 cm^-2 for urea production under a three-electrode configuration. The underlying mechanism can be described as the TB-induced compression shortening the Cu-Cu bond, creating Cu₂-pair pockets that geometrically matched CO₂ adsorption and enabled asymmetric activation to *CO, further strengthening Cu → CO π back-donation and building a *CO reservoir. Smoluchowski smoothing rendered ridge Cu sites electron-deficient, enriching NO₃ ^- near Cu₂-pair pockets for C-N coupling.