Iron oxide cluster induced barrier-free conversion of nitric oxide to ammonia

Abstract

Nitrogen oxide (NO) conversion to ammonia (NH₃) over iron oxide clusters is investigated using density functional theory calculations. The introduction of NO and H₂ over gas-phase Fe₄O₂ results in the formation of NH₃ and H₂O without activation barriers. The key reaction is barrier free conversion of NO to N and H₂O where the physical origin rests on negative–negative repulsion of NO over iron oxide clusters. The by-product H₂O can be a hydrogen source due to electrolysis or re-visiting Fe₄O₂ and hence, the reaction is self-sustainable. Furthermore, the above reactions are performed by depositing Fe₄O₂ clusters on graphene/Cu(111) where the barrier free conversion of NO to NH₃ is also observed, predicting that such reaction can be applicable. Thus, low temperature conversion of NO to NH₃ over Fe₄O₂ can be predicted. The detailed reaction pathway and mechanism are presented.