SERS activity of carbon nanotubes modified by silver nanoparticles with different particle sizes

Abstract

A two-dimensional (2D) surface-enhanced Raman scattering (SERS) substrate was fabricated by decorating carbon nanotube (CNT) films with Ag nanoparticles (AgNPs) in different sizes, via simple and low-cost chemical reduction and self-assembling methods. The change of Raman and SERS activity of carbon nanotubes/Ag nanoparticles (CNTs/AgNPs) composites with varying size of AgNPs was investigated with using rhodamine 6G (R6G) as a probe molecule. Meanwhile, the scattering cross section of AgNPs and the distribution of electric field of CNTs/AgNPs composite were simulated through finite difference time domain (FDTD) method. Surface plasmon resonance (SPR) wavelength is redshifted as the size of AgNPs increases, and the intensities of SERS and electric fields increase along with it. The experiment and simulation results showed a Raman scattering enhancement factor (EF) of 108 for the hybrid substrates.

Label-Free SERS Salivary Biosensor Based on Ni@Ag Core–Shell Nanoparticles Anchored on Carbon Nanofibers for Prediagnosis of Lung Cancer

“…Electromagnetic enhancement is primarily caused by a group of oscillating electron waves on the substrate, which is often observed for substrates abundant with free electrons and capable of producing localized surface plasmon resonance (LSPR) during excitation. − This leads to the formation of highly localized areas of LSPR-induced electromagnetic field amplification, known as hotspots in the gaps between the consecutive Ni@Ag core–shell nanoparticles. Hence, enhancement occurs when the analyte molecules come in the vicinity of the hotspots and enhancement decreases as the distance between the consecutive plasmonic Ni@Ag nanoparticles increases.…”