Using a photochemical method and chitosan to prepare surface-enhanced Raman scattering–active silver nanoparticles

In this paper, we report a new strategy for the preparation of surface-enhanced Raman scattering (SERS)-active silver nanoparticles (Ag NPs), using a photochemical method and the presence of chitosan (Ch). First, Ag substrates were subjected to electrochemical oxidation/reduction cycles (ORCs) in deoxygenated aqueous solutions containing 0.1 M HNO3 and 1 g L−1 Ch (pH 6.9, adjusted by adding 1 M NaOH), resulting in Ag+–Ch complexes. These substrates were then irradiated with UV light at various wavelengths to yield the SERS-active Ag NPs. A stronger SERS effect was observed on the SERS-active Ag NPs prepared by using UV irradiation at 310 nm. The pH of the solution and the presence of Ch during the preparation process both affected the resulting SERS activities.

SEM images of Ag NPs obtained after reducing Ag+-containing complexes in solutions of 0.1 M HNO3 containing 1 g L−1 Ch (pH 6.9, adjusted with 1 M NaOH) under irradiation with UV light of wavelength of 310 nm for 30 min.Figure optionsDownload as PowerPoint slideHighlights
► Prepare SERS-active Ag nanoparticles by using green process with aid of chitosan.
► The Ag-containing complex was irradiated with UV light to yield SERS activity.
► pH of the solution and the presence of Ch both affect the resulting SERS activities.