Facile Synthesis of Micron-Sized Hollow Silver Spheres as Substrates for Surface-Enhanced Raman Scattering

Abstract EN

A well-designed type of micron-sized hollow silver sphere was successfully synthesized by a simple hard-template method to be used as substrates for surface-enhanced Raman scattering.

4 Å molecular sieves were employed as a removable solid template.

[Ag(NH3)2]+ was absorbed as the precursor on the surface of the molecular sieve.

Formaldehyde was selected as a reducing agent to reduce [Ag(NH3)2]+, resulting in the formation of a micron-sized silver shell on the surface of the 4 Å molecular sieves.

The micron-sized hollow silver spheres were obtained by removing the molecular sieve template.

SEM and XRD were used to characterize the structure of the micron-sized hollow silver spheres.

The as-prepared micro-silver spheres exhibited robust SERS activity in the presence of adsorbed 4-mercaptobenzoic acid (4-MBA) with excitation at 632.8 nm, and the enhancement factor reached ~1.5 × 106.

This synthetic process represents a promising method for preparing various hollow metal nanoparticles.