Two-coordinate Cu(I) sites in ZIF-derived porous carbon enable high CO working capacity for CO/N₂ separation

Efficient separation of carbon monoxide (CO) from nitrogen (N₂) is vital for recycling steel industry by-product gases and advancing carbon-neutral chemical production. However, current Cu(I)-based π-complexation adsorbents suffer from excessive binding strength and low working capacity. Here we report thermally-dispersed open metal sites (OMS) with two-coordinated Cu(I) units, ( ≡ C-O)CuCl, anchored onto zeolite imidazolate frameworks (ZIFs) derived oxygen-containing porous carbons (ZPC), where the Cu···CO interaction strength is precisely moderated. The optimized adsorbent, 15Cu(I)/ZPC-1, with 15 mmol g⁻¹ Cu(I) dispersed in 10-30 Å pores, delivers a high CO working capacity of 3.21 mmol g⁻¹ (0.1-1 bar, 298 K), the highest among reported recyclable Cu(I)-based adsorbents. The analyses reveal that a low-symmetric trigonal ( ≡ C-O)CuCl···CO coordination geometry weakens π-backbonding, enhances working capacity. Process simulations predict that 15Cu(I)/ZPC-1 enables high productivity and low energy consumption. This work establishes OMS regulation in porous carbon as an effective strategy for efficient CO/N₂ separation.