Unleashing High Yield Urea Production by Pulse Electrodeposition of Bi/Cu via Co-reduction of N2 and CO2

Abstract

The expanding agricultural practices rely on carbon- and energy-intensive Bosch–Meiser processes for urea synthesis. Alternatively, electrochemical coupling of CO₂ and N₂ is emerging as a sustainable approach. Unfortunately, the high energy barrier for N₂ and CO₂ cracking for C–N bond coupling limits the urea synthesis efficiency. Herein, we have electrodeposited Bi on Cu foil via triple pulse voltage, and the fabricated Bi(0.01 V)@Cu electrode demonstrates a high yield rate of 646 μg h^–1 mg^–1_cat. of urea with 70.7% Faradaic efficiency at −0.45 V vs RHE. The isotopic labeling experiments assert that the produced urea is solely from the dissolved CO₂ and N₂ gases. More importantly, we have utilized in situ electrochemical Raman spectroscopy and Fourier transform infrared (FTIR) measurements to monitor the real-time formation of urea, further supported by a microelectrochemical approach using a Pt-microelectrode and the results were verified by density functional theory (DFT) analysis. Moving a step forward, plant growth and flowering upon addition of extracted urea have been demonstrated for practical application.