Developing an aqueous approach for synthesizing Au and M@Au (M = Pd, CuPt) hybrid nanostars with plasmonic properties

TL;DR

This paper presents a simple aqueous synthesis method for creating Au and M@Au hybrid nanostars with tunable plasmonic properties, enhancing their application in SERS detection.

Contribution

It introduces a general, facile synthesis strategy for anisotropic nanostars with controlled morphology and plasmonic features, expanding their potential in optical and sensing applications.

Findings

Successful synthesis of Au and M@Au nanostars with controlled morphology.

Enhanced SERS performance of nanostars for detecting trace molecules.

Identification of growth mechanisms influencing nanostar formation.

Abstract

Anisotropic Au nanoparticles show unique localized surface plasmon resonance (LSPR) properties, which make it attractive in optical, sensing, and biomedical applications. In this contribution, we report a general and facile strategy towards aqueous synthesis of Au and M@Au (M = Pd, CuPt) hybrid nanostars by reducing HAuCl4 with ethanolamine in the presence of cetyltrimethylammonium bromide (CTAB). According to electron microscopic observation and spectral monitoring, we found that the layered epitaxial growth mode (i.e., Frank-van der Merwe mechanism) contributes to the enlargement of the core, while, the random attachment of Au nanoclusters onto the cores accounts for the formation of the branches. Both of them are indispensable for the formation of the nanostars. The LSPR properties of the Au nanoparticles have been well investigated with morphology control via precursor amount and growth temperature. The Au nanostars showed improved surface-enhanced Raman spectroscopy (SERS) performance for rhodamine 6G due to their sharp edges and tips, which were therefore confirmed as good SERS substrate to detect trace amount of molecules.