A general approach to hybrid platform of Au nanoparticles on monolayer semiconductor for ultrasensitive Raman enhancement of 2D materials and molecule detection

The hybrid platform combining two-dimensional (2D) materials and noble metals has great potential to further enhance the performance of surface enhanced Raman spectroscopy (SERS). However, the fabrication process of metallic nanostructures may bring damage to 2D materials and also lack of general applicability. Here, we develop an approach for the fabrication of Au nanoparticles (AuNPs) on monolayer semiconductor through gold mediated mechanical exfoliation followed by a controllable etching in KI/I₂ solution. The proposed method and as-prepared hybrid SERS platform have been proved to have several advantages. (1) The fabrication of Au nanoparticles is mild and non-substrate-selective, which can be generally adapted to various substrate (e.g., ReSe₂, MoS₂ and PdSe₂). (2) The hybrid platform of AuNPs/2D materials can effectively enhance the Raman signals of the underneath 2D materials. For example, the Raman intensity of monolayer PdSe₂ in hybrid substrate is enhanced by about four times compared with that of bare PdSe_2. (3) The hybrid platform can dramatically enhance the detection limits of R6G molecule down to picomolar, approximately three to four orders of magnitude lower than that of bare 2D material counterpart. Our work provides a general approach for the fabrication of high-performance SERS hybrid substrate.