Pore Engineering for Directional CO₂ Enrichment in Urea Electrosynthesis

Electrochemical synthesis of urea from CO₂ and nitrate offers a sustainable pathway to address both carbon emissions and nitrogen pollution. However, achieving high C-N coupling selectivity remains challenging due to competing hydrogen evolution reactions and insufficient CO₂ utilization. Herein, we implement a nanopore-structure engineering strategy to precisely tailor pore length and surface chemistry in metal-free porous carbon frameworks. Oxygen-functionalized surfaces augment CO₂ binding affinity via dipole-quadrupole interactions, while elongated pores induce directional CO₂ enrichment by establishing a H₂O-deficient nanoenvironment that prolongs the residence time of CO₂ through capillary gating. This dual modulation of gas-liquid-solid interactions enhances urea selectivity and suppresses hydrogen evolution, yielding a 28% increase in Faradaic efficiency and 12% improvement in urea yield. Our findings propose a novel nanopore-level design concept that shall support the rational development of porous carbon supports across gas-liquid-solid electrocatalytic systems.