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@Pt₁₂@Pd₂₀ was more stable than two-shell Pt₁₃@Pd₂₀, while two-shell Pd₁₃@Pt₂₀ was more stable than three-shell Pt@Pd₁₂@Pt₂₀. 55-atom three-shell Pd@Pt₁₂@Pd₄₂ and Pt@Pd₁₂@Pt₄₂ were more stable than two-shell Pt₁₃@Pd₄₂ and Pd₁₃@Pt₄₂. 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 Pd₁₃@Pt₂₀. 33-atom NPs with Pt surface-shell afforded higher total magnetic moment than those with Pd surface-shell.