Single gold-nanoparticles-decorated silver/carbon nanowires as substrates for surface-enhanced Raman scattering detection

Abstract

Silver/carbon (Ag/C) core–shell nanowires with different thickness of shell were synthesized by a hydrothermal method and used as templates for fabricating gold nanoparticle-decorated Ag/C (Ag/C/AuNPs) nanowires. The Ag/C/AuNPs nanowires were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX). It was found that the number density and particle size of Au nanoparticles can be tuned by varying the concentration of Au precursor. Surface-enhanced Raman scattering (SERS) measurements showed that single Ag/C/AuNPs nanowire exhibited strong SERS effect. Rhodamine 6G (R6G) molecules, with an extremely low concentration (1.0 × 10⁻¹¹ M), were readily detected using single Ag/C/AuNPs nanowires. Detection of melamine molecules at concentrations as low as 1.0 × 10⁻⁷ M was used as an example to show the possible application of such Ag/C/AuNPs nanowires. In addition, the effect of benzoic acid on the detection of melamine was also investigated. It was found that the SERS spectrum profile and intensity of melamine is very sensitive to the presence of benzoic acid.