Regulating Multifunctional Oxygen Vacancies for Plasma-Driven Air-to-Ammonia Conversion

Area of Science:

• Catalysis and Materials Science
• Electrochemistry
• Plasma Science

Background:

• Current ammonia synthesis methods face challenges in nitrogen activation, product separation, and process complexity.
• Existing processes often rely on liquid phase intermediates, complicating scalability and efficiency.

Purpose of the Study:

• To develop a direct, scalable plasma-electrochemical process for gaseous ammonia production from air-generated nitrogen oxides (NOx).
• To decouple ammonia synthesis from liquid phase intermediaries and facilitate efficient product separation.

Main Methods:

• Utilized a plasma-electrochemical approach for direct gaseous ammonia production.
• Employed a strategy of plasma pretreatment and wet chemical calcination to create oxygen vacancies in Fe₂O₃ nanoparticles on Cu.
• Investigated the reduction of NOx to ammonia under ambient conditions.

Main Results:

• Achieved a significant ammonia production rate of 628 nmol·s⁻¹·cm⁻².
• Demonstrated nearly 100% faradaic efficiency for NOx reduction to ammonia.
• Successfully produced gaseous ammonia, simplifying separation processes.

Conclusions:

• The developed plasma-electrochemical process offers a scalable and efficient route for ammonia synthesis from air-generated NOx.
• The introduction of multifunctional oxygen vacancies in defective Fe₂O₃ nanoparticles is crucial for high performance.
• This method presents a promising alternative to traditional ammonia synthesis, operating under ambient conditions with direct gaseous product.