Geometrical features, stability and electronic properties of (Cu3Sn)n clusters

Abstract

Recently, significant advancements have been made in low-entropy Cu₃Sn catalysts, showcasing their efficient catalytic CO oxidation capabilities. Hence, the atomic models of the Cu₃Sn are worth established to further investigate their catalytic mechanisms. Here, the structural features and stability of (Cu₃Sn)_n clusters (n = 1–6) are investigated using the genetic algorithm combined with the density functional theory (DFT). The results reveal the structural evolution of these clusters from hollow cages to compact icosahedrons, where Cu atoms predominantly tend to grow together, while Sn atoms are dispersed at the edge positions. The E_b, E_f and Δ₂E analyses show that the icosahedral (Cu₃Sn)₃ has a higher stability than that of its neighbors. The molecular dynamics simulations demonstrates its stability even at 1000 K. The molecular orbitals and density of states reveal that the (Cu₃Sn)₃ has an 1S²1P⁶1D¹⁰2S²1F¹ superatomic electronic configuration. Electrostatic potential surfaces show that (Cu₃Sn)_n clusters have significant σ-hole regions at the Cu atomic sites, which can make the CO stretching frequency and bond length have a large red-shift. Moreover, the adsorption energy between the (Cu₃Sn)₃ and CO is the largest, reaching 1.17 eV. Our work provides inferences to the structural characteristics and adsorptions of the CuSn alloys at the atomic level.