Highly Efficient Electrosynthesis of Urea from CO₂ and Nitrate by a Metal-Organic Framework with Dual Active Sites

Electrosynthesis of urea from CO₂ and NO₃ ^- is a sustainable alternative to energy-intensive industrial processes. The main challenge hindering the progress of this technology lies in the development of advanced electrocatalysts that efficiently utilize abundant, low-cost CO₂ and nitrogen sources to yield urea with both high Faradaic efficiency (FE) and current density. In this work, we designed and prepared a new two-dimensional metal-organic framework (MOF), namely PcNi-Fe-O, constructed by nickel-phthalocyanine (NiPc) ligands and square-planar FeO₄ nodes, as the electrocatalyst for urea electrosynthesis. PcNi-Fe-O exhibits remarkable performance to yield urea at a high current density of 10.1 mA cm^-2 with a high FE(urea) of 54.1 % in a neutral aqueous solution, surpassing those of most reported electrocatalysts. No obvious performance degradation was observed over 20 hours of continuous operation at the current density of 10.1 mA cm^-2. By expanding the electrode area to 25 cm² and operating for 8 hours, we obtained 0.164 g of high-purity urea, underscoring its potential for industrial applications. Mechanism study unveiled the enhanced performance might be ascribed to the synergistic interaction between NiPc and FeO₄ sites. Specifically, NH₃ produced at the FeO₄ site can efficiently migrate and couple with the *NHCOOH intermediate adsorbed on the urea-producing site (NiPc). This synergistic effect results in a lower energy barrier for C-N bond formation than those of the reported catalysts with single active sites.