New Magic Au₂₄ Cluster Stabilized by PVP: Selective Formation, Atomic Structure, and Oxidation Catalysis

Area of Science:

• Nanomaterials Science
• Catalysis
• Computational Chemistry

Background:

• Magic number clusters represent specific, highly stable atomic arrangements.
• Controlling the synthesis of precise gold clusters is challenging.
• Poly(N-vinyl-2-pyrrolidone) (PVP) is a common polymer stabilizer.

Purpose of the Study:

• To selectively synthesize and characterize unprecedented magic number gold clusters (Au24Clx).
• To elucidate the atomic structure and electronic properties of Au24Clx clusters.
• To investigate the catalytic activity of Au24Clx:PVP clusters in aerobic oxidation reactions.

Main Methods:

• Kinetically controlled reduction in a microfluidic mixer.
• Aberration-corrected transmission electron microscopy (ACTEM) for structural analysis.
• Density functional theory (DFT) calculations for isomeric structure determination.
• X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) for electronic properties.

Main Results:

• Selective synthesis of Au24Clx (x=0-3) magic number clusters achieved.
• ACTEM and DFT revealed surface-bound atoms and isomeric structures.
• Electron-rich nature of clusters confirmed due to PVP interaction.
• Au24Clx:PVP demonstrated efficient catalysis for aerobic oxidation of benzyl alcohol derivatives.
• Kinetic studies identified hydride elimination as the rate-limiting step.

Conclusions:

• The coexistence of distinct isomers contributes to the unique optical properties of Au24Clx.
• PVP stabilization enhances the electron density of gold clusters, improving catalytic performance.
• Au24Clx clusters are effective catalysts for aerobic oxidation, with a well-defined reaction mechanism involving hydride elimination and oxygen activation.