Prism rather than tetrahedron: low-energy structures for gaseous gold clusters Au₁₀(O₂)_n⁺ by density functional calculations

The purpose of this study is to reveal the adsorption mechanism of oxygen molecules on gold clusters. density functional theory is employed to investigate the low-energy structure of multiple O₂ adsorption on the Au₁₀⁺ cluster and findings are compared with IR spectra. The nature of bonding of the O₂ molecule and Au₁₀⁺ cluster has been characterised through several metrics like binding energy, dissociation energy, bond length, and vibrational frequencies. The result shows that the lowest-energy structures are prism-shaped rather than tetrahedron-shaped, where only one O₂ is chemically adsorbed while others are physically adsorbed. Chemically adsorbed η²-O₂ behaves like free O₂^–, forming a single electron π bond with Au₁₀⁺, while physically adsorbed η¹-O₂ does not result in an effective chemical bond and behaves like free O₂. This study provides insights into the mechanism of oxygen molecule adsorption on gold clusters and can contribute to further research on the catalytic mechanism of gold clusters. <b>Highlights</b>Lowest energy structures are prism-shaped rather than tetrahedron-shaped, which is supported by IR spectrum and chemical hardness.Chemically adsorbed O₂ is activated and displays structural and spectral features of free O₂^–, while physically adsorbed O₂ is close to free O₂ in vibrational frequency and bond length.Chemical adsorption is equivalent to a single electron π bond while physical adsorption forms no effective chemical bond due to the lack of electronic pairing between Au₁₀⁺ and O₂. Lowest energy structures are prism-shaped rather than tetrahedron-shaped, which is supported by IR spectrum and chemical hardness. Chemically adsorbed O₂ is activated and displays structural and spectral features of free O₂^–, while physically adsorbed O₂ is close to free O₂ in vibrational frequency and bond length. Chemical adsorption is equivalent to a single electron π bond while physical adsorption forms no effective chemical bond due to the lack of electronic pairing between Au₁₀⁺ and O₂.