Insight into the mechanism on NO reduction over dual-atom Fe-Cu catalyst supported on N-dopped graphene: A DFT study

The mechanisms on NO reduction over dual-atom Fe-Cu catalyst supported on nitrogen-doped graphene were investigated by density functional theory (DFT) simulation. The adsorption characteristics of NO and the mechanisms of NO reduction over nitrogen-doped graphene supported single-atom Fe catalyst, single-atom Cu catalyst, and dual-atom Fe-Cu catalyst have been studied. Severe possible reaction pathways were found in the NO reduction over above catalysts and the energy barrier of each reaction steps was calculated. The most probably pathway of NO reduction over dual-atom Fe-Cu catalyst is NO molecules adsorbs on catalyst surface via Langmuir-Hinshelwood mechanism and directly reduced to N₂. Compared to single-atom catalysts, dual-atom catalyst offer more adsorption sites, thereby promoting the adsorption of NO and altering the NO reduction pathway. Additionally, the electron transfer between the dual atoms reduces the energy barrier for NO reduction, facilitating the progress of the NO reduction. With increasing reaction temperature and pressure, the rate of NO reduction over dual-atom Fe-Cu catalyst progressively increases. The H₂O and SO₂ have little impact on NO reaction over dual-atom Fe-Cu catalyst.