Gram-Scale Ammonia Synthesis via Electrochemical Nitrate Reduction Using Enzyme-Inspired Dual-Atomic Cu Catalyst

Area of Science:

• Green chemistry and catalysis
• Electrochemical engineering
• Materials science

Background:

• Electrocatalytic nitrate reduction (NO₃RR) offers a sustainable route to ammonia (NH₃) production.
• Developing highly active and stable electrocatalysts for efficient NO₃RR remains challenging.
• Nature's nitrite reductase utilizes dual-site copper for efficient nitrite conversion.

Purpose of the Study:

• To design and synthesize an enzyme-inspired electrocatalyst mimicking natural nitrite reductase for enhanced NO₃RR.
• To investigate the catalytic mechanism and performance of the designed catalyst for ammonia production.
• To achieve high-yield, continuous ammonia production from nitrate wastewater.

Main Methods:

• Construction of dual-atomic copper sites on polymeric carbon nitride (PCN-Cu-DAC).
• Electrochemical characterization and performance testing of the PCN-Cu-DAC catalyst.
• Mechanistic studies to understand the role of dual-atomic copper sites in proton transfer and nitrate adsorption.

Main Results:

• The PCN-Cu-DAC catalyst demonstrated significantly enhanced proton transfer and nitrate adsorption.
• Achieved remarkable ammonia yields of 467 mg h⁻¹ mg⁻¹ cat. and 102 mg h⁻¹ cm⁻².
• Sustained an ammonia yield of 11 g d⁻¹ at 6 A for 360 hours, demonstrating excellent stability.

Conclusions:

• Mimicking natural enzyme active sites is a viable strategy for designing advanced electrocatalysts.
• The PCN-Cu-DAC catalyst shows great promise for practical applications in nitrate wastewater treatment and ammonia synthesis.
• This work paves the way for continuous, green ammonia production via electrocatalytic nitrate reduction.