Structure, stability, electronic and magnetic properties of monometallic Pd, Pt, and bimetallic Pd-Pt core-shell nanoparticles

The structure, stability, electronic and magnetic properties of 13-, 33- and 55-atom Pd, Pt monometallic and bimetallic core-shell nanoparticles (BCSNPs) were investigated using the density functional theory calculations. The results showed that Pt@Pd BCSNPs with a Pd surface-shell are thermodynamically more favorable than Pd@ Pt with a Pt surface-shell. Interestingly, 33-atom three-shell Pd@Pt-12@Pd-20 was more stable than two-shell Pt-13@Pd-20, while two-shell Pd-13@Pt-20 was more stable than three-shell Pt@Pd-12@Pt-20. 55-atom three-shell Pd@Pt-12@Pd-42 and Pt@Pd-12@Pt-42 were more stable than two-shell Pt-13@Pd-42 and Pd-13@Pt-42. The Pd@Pt BCSNPs with Pt surface-shell exhibited a negative charge, d-band-center upshift and high chemical activity, while the Pt@Pd BCSNPs with Pd surface-shell displayed a positive charge, d-band center downshift and low chemical activity. 13- and 55-atom NPs with Pd surface-shell displayed higher total magnetic moment than those with Pt surface-shell except Pd-13@Pt-20. 33-atom NPs with Pt surface-shell afforded higher total magnetic moment than those with Pd surface-shell.