Trace Cu-Induced Low C─N Coupling Barrier on Amorphous Co Metallene Boride for Boosting Electrochemical Urea Production

Abstract

The electrochemical C─N coupling of carbon dioxide (CO₂) and nitrate(NO₃^-) is an alternative strategy to the traditional high−energy industrial pathway for urea synthesis, which urgently requires the design of efficient catalysts to achieve high yield and Faraday efficiency (FE). Here, amorphous low-content copper-doped cobalt metallene boride (a-Cu_0.1CoB_x metallene) is designed for urea synthesis via electrochemical C─N coupling. The a-Cu_0.1CoB_x metallene can drive electrocatalytic C─N coupling of CO₂ and NO₃⁻ for urea synthesis in CO₂-saturated 0.1 m KNO₃ electrolyte, with 27.7% of FE and 312 µg h⁻¹ mg⁻¹_cat. of yield at −0.5 V, as well as superior cycling stability. The in situ Fourier transform infrared and theoretical calculations reveal that electronic effect between Cu, Co, and B causes Cu and Co as dual active sites to promote the adsorption of reactants. Furthermore, the introduced trace Cu reduces the reaction energy barrier of the C─N coupling to facilitate urea synthesis. This work provides a promising route for the optimization of Co-based metallene for the electrosynthesis of urea through C─N coupling.