Steering competitive N2 and CO adsorption toward efficient urea production with a confined dual site

Abstract

Electrocatalytic urea synthesis under mild conditions via the nitrogen (N₂) and carbon monoxide (CO) coupling represents an ideal and green alternative to the energy-intensive traditional synthetic protocol. However, this process is challenging due to the more favorable CO adsorption than N₂ at the catalytic site, making the formation of the key urea precursor (*NCON) extremely difficult. Herein, we theoretically construct a spatially isolated dual-site (D_S) catalyst with the confinement effect to manipulate the competitive CO and N₂ adsorption, which successfully guarantees the dominant horizontal N₂ adsorption and subsequent efficient *NCON formation via C–N coupling and achieves efficient urea synthesis. Among all the computationally evaluated candidates, the catalyst with dual V sites anchored on 4N-doped graphene (D_S-VN₄) stands out and shows a moderate energy barrier for C–N coupling and a low theoretical limiting potential of −0.50 V for urea production, which simultaneously suppresses the ammonia production and hydrogen evolution. The confined dual-site introduced in this computational work has the potential to not only properly address part of the challenges toward efficient urea electrosynthesis from CO and N₂ but also provide an elegant theoretical strategy for fine-tuning the strength of chemical bonds to achieve a rational catalyst design.