Decoupling the activity-selectivity trade-off via synergistic dual-site electrocatalysis to steer CN coupling selectivity toward urea electrosynthesis.

Abstract

Electrosynthesis of urea holds promise for carbon mitigation, pollutant valorization, and green chemical production, yet it is hindered by competitive adsorption and sluggish CN coupling. Here, we develop a dual-single-atom catalyst, wherein Fe and Ni are atomically dispersed on a CeO2 support (Fe3Ni1-CeO2). By spatially decoupling the activation of CO2 and NO3- onto distinct, highly specialized neighboring centers, the dual-site architecture not only circumvents competitive poisoning but also establishes unique pathways that modulate thermodynamics. Thus, Fe3Ni1-CeO2 achieves an outstanding urea yield rate of 65.9 mmol gcat.-1 h-1 alongside a Faradaic efficiency of 70.2% at -0.7 V (vs. the reversible hydrogen electrode, RHE). In situ spectroscopic characterization combined with the control experiments substantiate the reaction pathway. Fe1 sites predominantly facilitate the deep reduction of NO3- to produce *NH, while Ni1 sites are responsible for CO2 reduction to *CO. These intermediates subsequently undergo rapid CN coupling at spatially adjacent dual-site, forming the key *CONH2 intermediate. Crucially, the asymmetric microenvironment created by the adjacent Fe and Ni sites stabilizes the vital transition state, thereby significantly lowering the kinetic barrier and effectively addressing the activity-selectivity trade-off. This work presents a novel design paradigm for developing highly stable and selective electrocatalytic CN coupling systems.