Phyto‐Confined CeO _x with Synergistic Lattice Distortion and Oxygen Vacancies Drives Efficient Urea Electrosynthesis

Abstract Electrocatalytic urea synthesis from carbon dioxide and nitrates is hindered by sluggish multi‐electron kinetics and unclear C‐N coupling mechanism. Herein, lattice‐distorted CeO _x nanoparticles are introduced with abundant oxygen vacancies (O _V ), confined within a porous carbon framework ( d ‐CeO _x /PC), fabricated via a phyto‐hyperaccumulation confinement strategy. Precise structural modulation induces ultrasmall (≈2 nm), uniformly dispersed, contracted Ce─O bonds (≈2.29 Å) and creates a highly active environment for urea electrosynthesis. In situ ATR‐FTIR spectroscopy identifies key intermediates, confirming C‐N coupling pathway. Theoretical calculation reveals contracted bonds strengthen Ce 4f‐O 2p orbital hybridization, restricting lattice oxygen (O _L ) migration and slowing O _V diffusion/annihilation. Simultaneously, bond contraction induces localized electron redistribution around O _V . These O _V promote mixed Ce ³⁺ /Ce ⁴⁺ valence, while the highly covalent, contracted Ce─O bonds stabilize Ce ³⁺ , forming localized “electron reservoirs” for flexible multi‐step electron transfer. These synergistic effects enhance reactant (CO ₂ /NO ₃ ⁻ ) adsorption, stabilize key intermediates (*CO/*NO), and drastically lower the C‐N coupling energy barrier (*NO+*CO→*OCNO, 0.18 eV), while suppressing competing hydrogenation pathways to byproducts. The porous carbon framework further improves durability (>100 h) and active site accessibility. This reduction in C‐N barrier, identified as the key kinetic descriptor enabled by structural modulation, provides mechanistic insight for designing catalysts for sustainable urea production from waste.