Surface-enhanced Raman scattering using monolayer graphene-encapsulated Ag nanoparticles as a substrate for sensitive detection of 2,4,6-trinitrotoluene

Abstract

We developed a surface-enhanced Raman scattering (SERS)-active substrate based on chemical vapor deposition (CVD)-grown monolayer graphene-encapsulated silver nanoparticles (Ag NPs) and used it for the detection of 2,4,6-trinitrotoluene (TNT). Monolayer graphene-encapsulated Ag NPs can be used as a stable substrate for up to 2 months under aerobic exposure. The single layer of graphene can effectively stabilize the Ag NPs against oxidation and corrosion in the presence of H₂O₂, Na₂S and HNO₃. Due to the combination of the Ag NPs with graphene, the Raman signals of probe molecules were dramatically enhanced. This platform exhibits extraordinarily high sensitivity and excellent stability for the detection of TNT, with a limit of detection as low as 6.6 × 10⁻¹⁰ mol L⁻¹. This work provides a simple approach to fabricate graphene-encapsulated Ag NPs for sensitive SERS sensing of TNT after Fenton oxidation degradation.