Remote Carbon Monoxide Spillover Improves Tandem Urea Electrosynthesis

Area of Science:

• Electrochemistry
• Materials Science
• Sustainable Chemistry

Background:

• Traditional industrial urea synthesis is energy-intensive and relies on the Haber-Bosch process.
• Electrocatalytic urea synthesis from CO2 and nitrate offers a sustainable alternative but faces challenges with intermediate supply and catalyst efficiency.
• Existing catalysts struggle with efficient coupling of carbon monoxide (CO) and amino (NH2) intermediates, leading to low urea production and high energy use.

Purpose of the Study:

• To develop a novel electrocatalyst for efficient and sustainable urea synthesis.
• To overcome limitations in intermediate supply and coupling for CO2 and nitrate electroreduction.
• To achieve high urea production rates with reduced energy consumption.

Main Methods:

• Tandem electrosynthesis using ruthenium dioxide-supported palladium-gold alloys (Pd2Au1/RuO2).
• Catalyzing CO2 to CO conversion on Pd2Au1 and nitrate to NH2 conversion on RuO2.
• Investigating remote CO spillover mechanism facilitated by minimized work function difference.

Main Results:

• Achieved a record-high Faradaic efficiency for urea (FEurea) of 75.6±0.5%.
• Demonstrated a high urea production rate (rurea) of 73.5±0.8 mmol gcat-1 h-1.
• Attained ultralow energy consumption of 18.9 kWh kgurea-1 and over 160 hours of stable operation.

Conclusions:

• The Pd2Au1/RuO2 catalyst system enables efficient tandem electrosynthesis of urea.
• Minimized work function difference promotes effective CO spillover and intermediate coupling.
• This work represents a significant advancement towards practical, large-scale sustainable urea electrosynthesis.