Triggering zinc oxide nanostructure with gold and silver nanoparticles: A SERS-active hybrid Plasmonic construct

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Noble metal nanoparticles (Au NPs, Ag NPs) are crucial for Surface-Enhanced Raman Spectroscopy (SERS).
• Zinc oxide nanostructures (ZnO NSs) offer synergistic benefits when combined with noble metals for SERS.
• Developing versatile fabrication routes for complex nanostructures is essential for SERS applications.

Purpose of the Study:

• To develop a simple and generic route for simultaneously functionalizing ZnO NSs with Au NPs and Ag NPs.
• To investigate the SERS activity and underlying mechanisms of the resulting Au-ZnO-Ag NSs.
• To explore the potential of these nanostructures for advanced SERS applications.

Main Methods:

• Fabrication of Au-ZnO-Ag NSs using a simple, generic route.
• Characterization of nanostructure morphology and elemental composition using FESEM.
• Analysis of chemical states and electronic structures using XPS.
• SERS activity evaluation using Rhodamine 6G (R6G) with 633 nm and 532 nm laser excitations.

Main Results:

• The fabricated Au-ZnO-Ag NSs demonstrated significantly higher SERS activity compared to ZnO NSs alone.
• Diverse sizes and shapes of the Ag NP core in Au-ZnO-Ag NSs contributed to the strongest enhancement factor (EF).
• An EF of approximately 10^6 was achieved for the Au-ZnO-Ag NSs, indicating high SERS sensitivity.
• A charge transfer mechanism involving ZnO NSs influenced by both Ag NPs and Au NPs was proposed to explain the high EF.

Conclusions:

• A versatile fabrication approach for Au-ZnO-Ag NSs has been successfully demonstrated.
• The developed nanostructures exhibit excellent SERS performance, attributed to synergistic effects and charge transfer.
• This work provides insights into the plasmonic properties of complex SERS-active nanostructures and their potential for SERS applications.