Electronic transmission bridge via 3D N-doping steering urea electrosynthesis

Abstract

Electrochemical urea synthesis from CO₂ and NO emerges as a promising alternative to the energy-intensive Haber-Bosch process, yet efficient C-N coupling is limited by suboptimal electronic structures and reaction kinetics, even for high-atomic utilization single-atom catalyst (SAC). Here, a 3D nitrogen (3D N)-doped SAC design is reported, where the conventional Cu-N-C framework is reorganized into a quasi-octahedral Cu-N₅-C structure and serves as an “electronic bridge” to enable d-p-p hybridization and promote electron-mediated C-N bond formation. DFT calculations show that the 3D N bridge enhances π-electron acceptance from CO₂ into N p-orbitals and d-orbital electron backdonation from Cu to CO₂ π*-orbitals, strengthening C-N covalency and enabling ultrafast charge transfer. The 3D N doping shifts the Cu d-band center from -2.73 to -2.31 eV, improving intermediate adsorption and enabling a reaction pathway where proton-coupled electron transfer alternates with C-N coupling while reducing competing reactions. Ab initio molecular dynamics (AIMD) simulations further confirm the structural stability of the catalyst at 298 K, demonstrating no atomic agglomeration over a 10 ps period and underscoring the design of promising approaches for efficient electrochemical urea production synthesis. This study provides critical insights into electron-driven electrocatalysis mechanisms, offering a rational framework for designing high-performance catalysts for urea production.