Structural factors of Au₂₅ cluster as precursor to synthesize Au/Nb2O5 for low-temperature CO oxidation

Abstract

Gold (Au) catalysts have gained significant attention as effective materials for the low-temperature oxidation of carbon monoxide (CO), with their electronic and geometric structures playing a key role in regulating oxidative properties. A series of Au catalysts were prepared using well-defined Au clusters (Au₂₅(SC₁₂H₂₅)₁₈) as precursor, and the effects of structural factors on the CO oxidation activity of these catalysts were investigated, including the size of Au nanoparticles, the ligand removal percentage, and the proportion of Au^δ+/Au⁰. This work unveiled that the appropriate removal of ligands can improve the catalytic performance for CO oxidation. Moreover, the size of Au nanoparticles is negative correlation with the CO oxidation activity over Au/Nb₂O₅ catalysts with Au₂₅(SC₁₂H₂₅)₁₈ as a precursor or on the Au/Nb₂O₅ catalysts with Au_n(SC₁₂H₂₅)_m (m/n = 0.46) as a precursor, but the effect was more pronounced in the Au-based catalysts with precise atomic precursors. The prepared Au/Nb₂O₅ catalyst that was calcined at 300 °C exhibited excellent CO oxidation activity (T_50 %, the temperature at 50 % CO conversion) at 18 °C due to the small Au nanoparticle size and minimum residue of thiol ligand. We anticipate that this study will stimulate novel perspectives and contribute to the development of highly efficient and stable Au-based catalyst systems.