Step-by-Step Nanoscale Top-Down Blocking and Etching Lead to Nanohexapods with Cartesian Geometry

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• Designing complex nanostructures with controlled morphology is crucial for advanced material properties.
• Tip-selective decoration of noble metal nanoparticles presents synthetic challenges.
• Understanding structure-property relationships in plasmonic nanomaterials is key for applications.

Purpose of the Study:

• To develop a stepwise synthetic method for fabricating Au@Pt hexapods with specific morphology.
• To investigate the optical properties of the synthesized Au@Pt hexapods.
• To demonstrate the utility of Au@Pt hexapods in surface-enhanced Raman spectroscopy (SERS) for *in situ* electrooxidation monitoring.

Main Methods:

• Stepwise synthesis involving three distinct chemical reactions.
• Utilizing platinum (Pt) adatoms as etching masks on a gold (Au) truncated octahedron core.
• Controlled isotropic etching to form the hexapod structure with Pt nanoplates at the tips.

Main Results:

• Successful fabrication of Au@Pt hexapods with six elongated Au arms tipped with Pt nanoplates.
• Demonstrated unique optical properties in the near-infrared region due to the hexapod morphology.
• Proof-of-concept SERS-based monitoring of *in situ* carbon monoxide (CO) electrooxidation achieved.

Conclusions:

• The developed stepwise synthesis is effective for creating complex Au@Pt hexapod nanostructures.
• The unique morphology imparts valuable optical properties for sensing applications.
• The selective blocking and etching strategy offers a versatile approach for colloidal synthesis of tailored nanomaterials.