Unraveling the roles of iron in stabilizing the defective graphene-supported Pt[sbnd]Fe bimetallic nanoparticles

Abstract

The adsorption behaviors of PtnFe(55-n) (n = 0, 11, 13, 18, 28, 37, 42, 44, 55) nanoparticles (NPs) on single vacancy graphene (SVG) were studied using density functional theory. It is found that the PtFe bimetallic NPs prefer to be adsorbed on the SVG through the Fe atoms when Pt and Fe atoms are both on the surfaces, because the interactions between Fe atoms and SVG are stronger than those between Pt atoms and SVG. Based on the density of states, molecular orbital and charge difference density analyses, the Fe atoms in the NPs can strongly interact with the sp2 dangling bonds and the π orbitals near the vacancy in the SVG at the same time. The interactions between the Pt atoms and the π orbitals are very weak. Meanwhile, due to the interactions between the Pt and Fe, the d-band centers of the Pt and Fe atoms in the NPs shift to lower energy, and the adsorption energies of PtnFe(55-n) (n = 18, 37, 42 and 44) NPs on the SVG are decreased compared with that of Pt55.