Ni-Fe Dual-Site Polymer Catalyst for High Performance and Stable Electrochemical Urea Synthesis from CO2 and NO3.

The electrochemical synthesis of urea from nitrate (NO3 -) and carbon dioxide (CO2) presents a sustainable alternative to conventional methods, mitigating pollution and reducing energy consumption. Herein, a rationally designed Ni-Fe bimetallic pyromellitic acid polymer catalyst (Ni-PMDA@Fe) is developed for efficient urea electrosynthesis. This metal-organic polymer provides structural robustness, abundant active sites, and a tunable coordination environment, optimizing C-N coupling kinetics. Ni-PMDA@Fe achieves a urea yield of 449.56 mg h-1 gcat -1 and a Faradaic efficiency (FE) of 41.06% at -0.5 VRHE, significantly surpassing monometallic controls (Ni-BDC, Ni-PMDA). Fe incorporation modulates the electronic structure of Ni, enhances charge transfer, and stabilizes key reaction intermediates, enabling synergistic NO3 -/CO2 coupling. Comprehensive characterization confirms homogeneous Fe doping and a dual-metal-site configuration. Unlike single-atom or monometallic systems, the Ni-Fe dual-site architecture optimally tunes the adsorption kinetics of critical intermediates. The catalyst maintains a FE exceeding 30% over a 30 h stability test, demonstrating robust operational stability. Furthermore, techno-economic analysis (TEA) indicates competitive production costs when powered by renewable energy, highlighting scalability potential. This word demonstrates a practical pathway for sustainable urea synthesis by converting pollutants (NO3 -/CO2) into value-added product, thereby contributing to decarbonizing fertilizer production and mitigating nitrogen pollution.