Core@shell, Au@TiO_x nanoparticles by gas phase synthesis.

Area of Science:

• Nanomaterials Science
• Surface Chemistry
• Materials Engineering

Background:

• Core-shell nanoparticles offer unique properties by combining different materials.
• Controlling nanoparticle synthesis at the gas phase is crucial for precise structural and chemical control.
• Titanium oxide shells are of interest for catalytic and electronic applications.

Purpose of the Study:

• To report the gas phase synthesis and characterization of multifunctional gold@titanium oxide (Au@TiO_x) core@shell nanoparticles.
• To investigate the structural and chemical properties of the synthesized nanoparticles.
• To confirm the insulating behavior of the titanium oxide shell.

Main Methods:

• One-step gas phase synthesis using a multiple-ion cluster source.
• In-flight oxidation and soft-landing of nanoparticles.
• Characterization using X-ray photoemission spectroscopy (XPS) and other techniques.

Main Results:

• Successfully synthesized Au@TiO_x nanoparticles with 6 nm Au cores and 1 nm TiO_x shells.
• Au cores displayed icosahedral (44%) and decahedral (66%) crystalline structures.
• The TiO₂ shell (79%) was amorphous and exhibited highly electrical insulating behavior, confirmed by XPS charging effects.

Conclusions:

• The one-step gas phase synthesis is effective for producing pure, multifunctional Au@TiO_x core@shell nanoparticles.
• The synthesized nanoparticles possess distinct core and shell properties, including crystalline gold and insulating titanium oxide.
• The demonstrated insulating nature of the TiO_x shell opens possibilities for electronic and catalytic applications.