Structure stability and electronic properties of PtmIrn(m+n = 8-10) and adsorption sites of NO on Pt-Ir Clusters at the DFT Level

The geometrical structures, stability and electronic properties of PtmIrn and PtmIrnNO (m+n=8−10) clusters have been studied by using density functional theory (DFT). Simple cube evolution pattern is revealed for Ir8−10 and Ir-rich clusters. The curve of the second-order energy difference of PtnIr(9−n) clusters shows the evident even–odd oscillations, indicating that PtIr8, Pt3Ir6, Pt5Ir4 and Pt7Ir2 clusters are more stable than their neighbors. The minimum excess energies values are seen for Pt7Ir, PtIr8 and Pt2Ir8, which means that these clusters show the stronger mixing tendency. Analysis of magnetic properties shows that the total magnetic moment contributed from Ir and Pt atoms, and the magnetic moment mainly comes from localization of the d orbit electron. All ground-state structures show an adsorption of NO at the top site of the bare cluster via the N atom. In all of the alloy clusters, NO molecule prefers to be adsorbed near the Ir atom site. Fukui function is an accurate predictor of the reactivity on a specific adsorption site in Pt–Ir alloy clusters.