Promoting direct C─N coupling via NO intermediate modulation for highly selective electrochemical urea synthesis

Area of Science:

• Electrochemistry
• Catalysis
• Sustainable Chemistry

Background:

• Electrochemical urea synthesis from CO2 and NO3- is promising but hindered by slow C-N coupling and competing NH3 formation.
• Controlling reaction intermediates is key to improving selectivity and efficiency.

Purpose of the Study:

• To develop a highly selective electrochemical urea synthesis pathway.
• To investigate the role of nitric oxide (NO) intermediates on diatomic sites for urea formation.
• To suppress competing ammonia (NH3) byproduct formation.

Main Methods:

• Utilized molybdenum-manganese (Mo-Mn) diatomic sites to modulate NO intermediate behavior.
• Investigated NO surface coverage and binding energy effects on reaction pathways.
• Compared Mo-Mn sites with copper-manganese (Cu-Mn) dual sites.

Main Results:

• Mo-Mn sites achieved 93.3% N selectivity towards urea with a yield rate of 35.16 mmol/h/g and 48.1% Faradaic efficiency at -0.6 V vs RHE.
• High NO surface coverage on Mo-Mn sites promoted NO dimerization and efficient CO insertion for urea synthesis.
• Cu-Mn sites showed weak NO adsorption, favoring NH3 formation (86.2% N selectivity).

Conclusions:

• A NO-mediated strategy using Mo-Mn diatomic sites enables efficient and highly selective electrochemical urea synthesis.
• Controlling NO intermediate behavior is crucial for optimizing urea production and minimizing ammonia byproduct.
• This approach offers a sustainable route for urea synthesis with improved efficiency.