Copper Atom Pairs Stabilize *OCCO Dipole Toward Highly Selective CO₂ Electroreduction to C₂H₄

Deeply electrolytic reduction of carbon dioxide (CO₂) to high-value ethylene (C₂H₄) is very attractive. However, the sluggish kinetics of C-C coupling seriously results in the low selectivity of CO₂ electroreduction to C₂H₄. Herein, we report a copper-based polyhedron (Cu2) that features uniformly distributed and atomically precise bi-Cu units, which can stabilize *OCCO dipole to facilitate the C-C coupling for high selective C₂H₄ production. The C₂H₄ faradaic efficiency (FE) reaches 51 % with a current density of 469.4 mA cm^-2, much superior to the Cu single site catalyst (Cu SAC) (~0 %). Moreover, the Cu2 catalyst has a higher turnover frequency (TOF, ~520 h^-1) compared to Cu nanoparticles (~9.42 h^-1) and Cu SAC (~0.87 h^-1). In situ characterizations and theoretical calculations revealed that the unique Cu2 structural configuration could optimize the dipole moments and stabilize the *OCCO adsorbate to promote the generation of C₂H₄.