Kinetically matched C-N coupling toward efficient urea electrosynthesis enabled on copper single-atom alloy

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science
• Sustainable Chemistry

Background:

• The Bosch-Meiser process for urea production is energy-intensive and relies on fossil fuels.
• Electrochemical synthesis of urea from CO2 and NO3- offers a sustainable alternative but faces challenges in reaction kinetics and intermediate management.
• Existing catalysts struggle with low urea yield rates and Faradaic efficiency due to complex co-reduction pathways.

Purpose of the Study:

• To develop a highly efficient catalyst for electrochemical urea synthesis from CO2 and NO3-.
• To overcome kinetic limitations and improve C-N coupling efficiency in urea electrosynthesis.
• To provide a sustainable and efficient alternative to the traditional Bosch-Meiser urea production method.

Main Methods:

• Design and synthesis of a single-atom copper-alloyed palladium catalyst (Pd4Cu1) supported on FeNi(OH)2.
• Electrochemical characterization to evaluate urea yield rate and Faradaic efficiency.
• In-situ spectroscopy and theoretical calculations to elucidate reaction mechanisms and active sites.

Main Results:

• The Pd4Cu1/FeNi(OH)2 catalyst achieved a high urea yield rate of 436.9 mmol gcat.-1 h-1 and a Faradaic efficiency of 66.4%.
• The catalyst demonstrated excellent stability over 1000 hours of operation.
• Cu doping and the Pd-Cu dual-site interface were found to regulate kinetics and stabilize key intermediates (*CO and *NH2) for efficient C-N coupling.

Conclusions:

• Atomically dispersed Cu in the Pd lattice promotes nitrate reduction to *NH2.
• The Pd-Cu dual-sites effectively lower the energy barrier for the crucial C-N coupling step.
• This work presents a promising single-atom catalyst for efficient and sustainable electrochemical urea synthesis.