One-pot green synthesis of flower-liked Au NP@GQDs nanocomposites for surface-enhanced Raman scattering

Abstract

The Au nanoparticles (Au NPs) with bumpy shapes take the advantages of the stronger localized surface plasmon resonance (LSPR) and more hot spots, which cause them to be the talented surface-enhanced Raman scattering (SERS) substrate. In this work, we reported a one-pot, rapid and green method to fabricate mutli-branched Au nanoparticle@graphene quantum dots (Au NP@GQDs) core-shell nanocomposites via using GQDs as the reducer without adding any other reagents for the first time. The hybrids with a mean diameter of ca. 47 nm have ultrathin 1-nm-thick GQDs shells which coat the flower-liked Au cores. The core-shell structure could provide a win-win pattern to substantially enhance the SERS signals of the dye molecules owing to the GQD coating for its high affinity to absorb the analytes and the bumpy Au NP-core for strong improvement of the LSPR. The Au NP@GQDs exhibited remarkably high SERS activity on different charged dyes, which revealed its universality on SERS detection. Further application of the nanocomposites for simple, sensitive and lable-free SERS detection of malachite green (MG), one of the illegal additives in aquaculture, was conducted, which revealed a superior SERS signals with the enhancement factor of 1.4 × 104 and the minimum detected concentration was as low as 0.5 nM. Moreover, the fantastic SERS repeatability and good structural stability also demonstrated the potential for SERS application. These properties make the flower-liked Au NP@GQDs a promising SERS substrate to detect the banned dye pollutants in the aquaculture and additive colorants in food industry.