A novel sensitive and stable surface enhanced Raman scattering substrate based on a MoS2 quantum dot/reduced graphene oxide hybrid system

Abstract

A MoS₂ quantum dot/reduced graphene oxide (MoS₂ QD/rGO) nanocomposite has been synthesized by a simple hydrothermal approach. For the first time, the MoS₂ QD/rGO composite is used as a highly sensitive and stable surface enhanced Raman scattering (SERS) substrate to detect trace amounts of molecular species. The lowest detection limit (LOD) for rhodamine 6G (R6G) is as low as 1 × 10⁻⁹ M with the maximum enhancement factor (EF) of up to 1.20 × 10⁷, which is the best among the non-noble metal SERS materials. For practical applications, the MoS₂ QD/rGO SERS substrate is also used to detect methylene blue (MB) in deionized water and river water. The LOD (1 × 10⁻⁸ M) is obtained in river water, which demonstrates the high feasibility for multi-molecule detection and vast potential ability for the detection of chemical and biological molecules. The enhancement mechanism of the MoS₂ QD/rGO SERS substrate is studied, and the large enhancement of the SERS signal is due to the charge transfer (CT) state formed at the interface of the 1T-phase MoS₂ QDs with small size and ultrathin slices and organic molecules. The chemical enhancement of rGO also contributes to the SERS enhancement. The study paves a new way for designing a novel MoS₂ QD-based SERS substrate.