One-step synthesis of few-layer MoS2/Au nanostructures mediated by colloidal gold exfoliation with potential for surface-enhanced Raman scattering applications

• One-step approach to fabricate MoS 2 /AuNPs composites using liquid-phase exfoliation; • For the first time, Au nanoparticles are used as an exfoliating and stabilizing agent; • Sonication time induces distinct MoS 2 /AuNPs composite with varied morphologies; • MoS 2 /AuNPs sonicated for 30 min show higher SERS sensitivity for adenine; Liquid-phase exfoliation (LPE) is a widely used top-down approach for producing two-dimensional (2D) materials on a large scale, including transition metal dichalcogenides (TMDs). Conventional LPE procedures face significant challenges, namely the use of fossil-derived organic chemicals, such as solvents and stabilizing agents. However, the use of colloidal nanoparticles or inorganic nanostructures as stabilizing agents to exfoliate TMDs has been less explored despite offering the possibility to synthesize composites with unique properties. This research reports an innovative one-step approach for fabricating 2D MoS 2 /AuNPs composites with distinct morphologies using an ultrasound-assisted LPE. This method comprises the exfoliation of MoS 2 commercial powders (bulk) using colloidal Au nanoparticles (AuNPs) and ultrasound waves, resulting in the synthesis of distinct plasmonic-based composites, depending on the sonication time. Several parameters were investigated to explore the production of MoS 2 /AuNPs composites, including the size and the coating of the AuNPs and the MoS 2 bulk/AuNPs ratio. As a proof of concept, we have assessed the surface-enhanced Raman scattering (SERS) sensitivity of these nanocomposites for the biodetection of adenine. Selected samples of 2D MoS 2 /AuNPs composites sonicated for 30 min were shown to be more sensitive to detecting adenine than the composite components alone (2D MoS 2 nanosheets and AuNPs).