Theoretical Study on No Oxidation Using Single Metal Atom Catalysis Embedded Graphene with N4 Vacancy

Abstract

This work investigates the potential NO oxidation schemes using a graphene with N4 vacancy (GrN4) monolayer doped with transition metals (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) for single-atom catalysis (SAC). The GrN4 monolayer is proven capable of greatly suppressing the clustering tendency of TM atoms due to its strong binding ability. Moreover, the Ti-GrN4 systems exhibit considerable affinity towards both NO and O2, meeting a fundamental criterion for kick-starting the catalytic cycle. Three dissimilar mechanisms: Eley-Rideal (ER), Langmuir-Hinshelwood (LH), and trimolecular Eley-Rideal (TER) mechanisms were examined for the NO oxidation in Ti-GrN4 SAC. The calculated activation barriers indicate that the LH pathway is the preferred mechanism, in which the NO+O2 reaction can form the OONO intermediate, then generate and release NO2 molecules. Therefore, Ti-supported GrN4 has the potential to be a strong single-atom catalyst for NO oxidation at low temperatures.

Keywords: NO oxidation, single metal atom catalysis, graphene with N4 vacancy, DFT calculations, oxidation mechanism