Nano-confinement engineering boosts C-N coupling for urea electrosynthesis

Area of Science:

• Electrochemistry
• Materials Science
• Sustainable Chemistry

Background:

• Electrochemical co-reduction of carbon dioxide (CO2) and nitrate offers a sustainable pathway for urea synthesis.
• Current methods face challenges with kinetic limitations and poor intermediate interactions, leading to low urea yields.

Purpose of the Study:

• To engineer a nano-confined bimetallic catalyst for enhanced urea synthesis.
• To overcome kinetic barriers and improve intermediate interactions in CO2 and nitrate electro-reduction.

Main Methods:

• Fabrication of a copper-ruthenium (CuRu) bimetallic catalyst confined within mesoporous carbon hollow spheres (MCHS).
• Electrochemical testing at high current densities (250 mA cm-2) with long-term stability assessment (125 hours).
• In situ spectroscopy and computational modeling to analyze reaction mechanisms and the effect of nano-confinement.

Main Results:

• Achieved a high urea yield of 12.51 g h-1 gcat-1 with 125-hour stability.
• Nano-confinement shifted the C-N coupling pathway from *COOH-*NH2 to the kinetically favored *OCO-*NO intermediates.
• Optimized pore-size engineering (4-11 nm) improved reactant transport and intermediate retention, enhancing selectivity.

Conclusions:

• Nano-confinement is a versatile strategy for controlling multi-step electrocatalytic processes.
• The engineered CuRu/MCHS catalyst demonstrates a promising route for sustainable urea production.
• This approach offers significant potential for advancing sustainable chemical synthesis through precise catalyst design.