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 (DS) 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 (DS-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.