Designing Molecular Reactor of Interlayer Dual-Atom Toward Urea Electrosynthesis

Electrocatalytic C─N coupling offers a sustainable alternative to energy-intensive industrial processes for urea synthesis. Herein, we design conjugated polymer-based molecular reactors featuring interlayer diatomic Cu–N₄ sites and precisely tunable spacings (4.0, 4.6, and 5.7 Å) to optimize CO₂ and nitrate coupling. The 4.0 Å-spaced copper polyphthalocyanine (CuPPc-4.0) delivers a remarkable urea yield rate of 460.0 mmol h⁻¹ g⁻¹ with 26.1% Faradaic efficiency at −1.3 V (versus RHE), outperforming wider-spaced analogs. The optimal 4.0 Å cavity spatially confines reactants and intermediates, matching urea's molecular dimensions (3.5 Å), thereby enhancing C–N coupling and urea synthesis activity, while the layered AA stacking structure stabilizes unbonded diatomic Cu configurations, preventing aggregation and ensuring durability. Mechanistic studies reveal that while ball-milling treatment increases single-atom exposure, it disrupts the layered architecture and eliminates interlayer diatomic sites, reducing activity by about 50%. This work demonstrates a multidimensional catalyst design integrating atomic precision and molecular confinement for sustainable electrosynthesis.