Tuning Cu–Cu Spacing in Single‐Atomic Layer Cu Catalysts for Efficient and Stable CO ₂ ‐To‐C ₂ H ₄ Electroreduction

The transition to sustainable energy relies on the efficient conversion of CO₂ into specific multi-carbon (C₂₊) products, yet this process is severely hindered by the slow kinetics of C─C coupling and uncertain product selectivity. Single-atom catalysts (SACs) exhibit promising catalytic performance but suffer from a fundamental limitation: their lack of contiguous active sites impedes C─C coupling. Herein, we report an innovative isotropic 2D Cu single-atomic-layer catalyst anchored on amorphous carbon substrate, designed to enhance C─C coupling and C₂₊ selectivity. By stabilizing Cu^δ ⁺ species and precisely tuning the Cu-Cu spacing to 2.35 Å-matching the C─C bond length of ethylene (C₂H₄), which significantly promotes C₂H₄ production. The catalyst achieved a remarkable Faradaic efficiency of 78.6% for C₂H₄ at -0.8 V versus the reversible hydrogen electrode, accompanied with high stability over 120 h. These findings not only elucidate the profound impact of spatially controlled active sites in complex multi-step reactions but also represent a significant leap forward in CO₂ conversion technologies, offering great potential for sustainable carbon utilization and addressing global energy transition challenges.