MoS2–Ag Nanocomposite-Based SERS Substrates with an Ultralow Detection Limit

Two-dimensional (2D) materials have been found to work efficiently for surface-enhanced Raman spectroscopy (SERS) owing to their electronic properties, tunable band gap, and layered structure with high absorption power. In this work, we have synthesized different morphologies of the MoS2, including the flower, interconnected nanoplates, and sheets, by the facile hydrothermal method to explore their morphological dependence for SERS application. The SERS substrate prepared with the nanoplate morphology MoS2 structures shows excellent detection up to 10–9 M concentration of rhodamine B (RhB) dye. RhB dye has genotoxic and carcinogenic effects on human as well as aquatic life, and it is illegally used as a food adulterant despite the prohibition. Thus, sensitive detection of RhB even at low concentrations is highly desired. MoS2 nanoplates have been functionalized with Ag nanoparticles (NPs) to optimize the MoS2 SERS performance. The MoS2–Ag nanocomposite SERS substrates successfully detect an ultralow concentration of 10–15 M of RhB dye with an enhancement factor of 9.2 × 107. A charge transfer mechanism between RhB molecules and MoS2 is proposed along with the contribution of Ag NPs in ultralow SERS detection.