Plasma for nitrogen fixation by using N₂/O₂ mixture: Reaction pathway, energy flow, and plasma reactor

When N-2/O-2 mixture is used for nitrogen fixation (NF), researchers believe that the Zeldovich mechanism is the main pathway for NO formation. However, there is still debate on whether N-2 participates in the Zeldovich mechanism through vibrational excitation or electronic excitation of the N2(A) state. This ambiguity has led to uncertainty regarding which type of plasma can achieve higher efficiency. Furthermore, the most significant obstacle to plasma-assisted NF is the high energy consumption. Gaining a deeper understanding of the energy flow in the discharge process is crucial for improving NF energy efficiency in the future. Therefore, this paper provides an overview of the research on these topics. Finally, various new plasma NF devices reported in recent years will also be discussed.