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From molecules to particles: How do gold nanoclusters revolutionize our understanding of materials?
With the rapid development of nanotechnology, the research on gold nanoclusters has attracted widespread attention in the scientific community. These tiny gold particles not only have the potential to change our traditional understanding of material structure, but also show great potential in high-tech applications such as optoelectronics and catalysis. Their diameter is less than one micrometer and can be discrete molecules or larger colloidal particles. For materials scientists, the study of these gold nanoclusters is not only an in-depth exploration of granular matter, but also an important discovery of the relationship between material structure and performance.
Bare gold nanoclusters and structural studies
Bare gold clusters are gold clusters without a stabilizing ligand shell, which can be synthesized and studied in vacuum using molecular beam techniques. The scientists explored the structure of these clusters using techniques such as anion photoelectron spectroscopy, far-infrared spectroscopy and electron diffraction. The study showed that the structure of bare gold nanoclusters is significantly different from that of ligand-stabilized gold clusters, indicating that the chemical environment has a crucial influence on the structure of gold clusters.
For example, Au20 forms a perfect tetrahedron, with the packing of its gold atoms closely resembling the atomic arrangement of the face-centered cubic (fcc) structure of metallic gold.
Ligand-stabilized gold cluster structures
Different from the exploration of bare gold clusters, ligand-stabilized gold clusters present more complex structures. When the size of gold particles decreases, their face-centered cubic structure transforms into a central icosahedral structure, such as Au13. This transformation enhances the stability of the gold clusters.
Icosahedral gold clusters are found in many gold clusters, connected by vertex sharing, face fusion, and interpenetrating bi-icosahedrons.
Discrete gold clusters and their applications
Well-defined molecular clusters commonly contain organic ligands, which must be removed to generate bare gold clusters in catalytic applications. This is usually achieved by incineration at high temperatures, but can also be accomplished chemically at lower temperatures.
Colloidal gold clusters and their optical properties
Gold clusters can also exist in colloidal form, often with surface coatings of alkylthiols or proteins. These gold particles have potential applications in immunohistochemical staining. Metal nanoparticles show strong absorption properties in the visible light region, which enhances their potential for application in the development of optical devices.
The wavelength of the surface plasmon resonance (SPR) band depends on the size and shape of the nanoparticles.
Catalytic properties of gold clusters
The catalytic potential of gold clusters is also outstanding in environmental catalysis. For example, when gold clusters are implanted on the surface of FeOOH, they can catalyze the oxidation of CO at ambient temperature. Furthermore, the catalytic activity of gold clusters on TiO2 supports can be carried out at extremely low temperatures, showing a strong correlation between their structure and catalytic performance.
The structural characteristics of gold nanoclusters affect their catalytic properties, which makes it an important topic to study the effects of their size and structure on catalytic properties.
End
The study of gold nanoclusters not only deepens scientists' understanding of nanomaterials, but also gives rise to a variety of new application possibilities. How these tiny particles will grasp the core of future materials science and what boundaries of knowledge and technology will they reveal will undoubtedly be an important direction for future exploration by the scientific community.
