Relative Stabilities of M₁₃@Pt₄₂ Core‐Shell Particle (M = 3d Transition Metals) and Its Non‐Core‐Shell Structure: Theoretical Insight

Core‐shell (CS) particle consisting of Pt shell and base metal core is one of promising candidates of excellent electrode catalyst for fuel cell, because it is highly active and highly stable like Pt particle but less expensive than Pt particle. However, its stability has been unclear. Herein, icosahedral M 13 @Pt 42 (M = 3 d transition metals, Sc to Cu) CS particles consisting of Pt 42 shell and M 13 core are systematically investigated using DFT calculations. The CS structures of Co 13 @Pt 42 , Ni 13 @Pt 42 , and Cu 13 @Pt 42 are calculated to be more stable than their non‐core‐shell (NCS) structures in which one 3d metal atom of the M 13 core is exchanged with one Pt atom of the Pt 42 shell. For Sc 13 Pt 42 , Ti 13 Pt 42 , V 13 Pt 42 , Cr 13 Pt 42 , Mn 13 Pt 42 , and Fe 13 Pt 42 , on the other hand, the NCS structure is more stable than the CS one. Small deformation energy of the Pt 42 shell compared to that of the Pt 41 M shell and small stabilization energy by Pt–M exchange between the Pt 42 shell and the M 13 core are particularly important for stabilizing the CS structure. Late 3d metal elements in the first transition series of the periodic table such as Co, Ni, and Cu are suitable for producing a stable M 13 @Pt 42 CS particle because their electronegativities are larger than those of the early and middle 3d transition metal elements and their atomic sizes are smaller than those of the early 3d metal elements such as Sc and Ti atoms. O 2 adsorption to M 13 @Pt 42 (M = Co, Ni, and Cu) CS particle occurs at the edge Pt atom and the vertex Pt atom in a side‐on manner. The adsorption energies of O 2 molecule to Co 13 @Pt 42 , Ni 13 @Pt 42 , and Cu 13 @Pt 42 CS particles are smaller than that to Pt 55 particle, indicating that the M 13 core decreases the reactivity of the Pt 42 shell for O 2 adsorption.