Ammonia electrosynthesis from nitrate using a stable amorphous/crystalline dual-phase Cu catalyst

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis
• Sustainable Chemistry

Background:

• Electrocatalytic nitrate reduction offers a sustainable route for ammonia synthesis using renewable energy.
• Current limitations include low catalytic activity and poor long-term stability of electrocatalysts.
• Ammonia is a crucial chemical feedstock and energy carrier.

Purpose of the Study:

• To develop a stable and highly active electrocatalyst for ammonia electrosynthesis.
• To improve the efficiency and durability of the nitrate reduction reaction for ammonia production.
• To demonstrate the scalability of the developed catalyst system.

Main Methods:

• Synthesis of a stable amorphous/crystalline dual-phase copper (Cu) catalyst.
• Electrocatalytic nitrate reduction reaction measurements under varying conditions.
• Long-term stability testing and performance evaluation at high current densities.
• Scale-up demonstration using a larger electrode size.

Main Results:

• Achieved high ammonia partial current density (3.33 A cm⁻²) and formation rate (15.5 mmol h⁻¹ cm⁻²) at 2.6 V.
• Demonstrated remarkable stability, maintaining ~90% Faradaic efficiency at 1.5 A cm⁻² for 300 hours.
• Scaled-up system (100 cm² electrode) produced ammonia at a rate of 11.9 g h⁻¹ at 160 A.

Conclusions:

• The dual-phase Cu catalyst significantly enhances ammonia electrosynthesis performance and stability.
• Stable amorphous Cu domains are key to promoting intermediate adsorption and improving reaction kinetics.
• This work highlights the potential of stabilizing metastable amorphous structures for advanced electrocatalysis.