Controllable Preparation and Size-Dependent SERS Performance of 35–410 nm Quasi-spherical Au NPs

Abstract

Uniform Au NPs with definite but different sizes will serve as a perfect model for studying the influence of NP size on surface-enhanced Raman scattering (SERS) performance. In this study, using tri-hydroxymethyl aminomethane (Tris-base) as a stabilizer and FeCl2 as a reducing agent, Au NPs with the size of 110–410 nm were prepared by a one-step method by simply changing the amount of FeCl2. In the preparation of small particle size Au NPs, sodium citrate was introduced as an auxiliary stabilizer, and 35–85 nm Au NPs were prepared in one step. In addition, the synthetic Au NPs of different sizes were loaded onto the glass substrate and 4-MOTP was used as the probe molecule to monitor their SERS properties. The results showed that the SERS activity results showed a “volcanic shape” with the change of nanoparticle size at a fixed excitation wavelength. The 160 nm Au NPs have the best SERS performance when the excitation wavelength is 633 nm.