Improving the SERS effect of van der Waals material by intercalation strategy

Intercalation is a means to effectively adjust the electronic structure and optoelectrical properties of van der Waals (vdW) layered materials, which is expected to improve its low surface enhanced Raman scattering (SERS) effect. In this work, H+ intercalation into a single vdW MoO3 nanosheet by a simple local intercalation method is demonstrated. It's found that H+ intercalation significantly improve the Raman signal of MoO3 to R6G molecules. This SERS enhancement comes from the improved charge transfer (CT) between the substrate and the molecule. Detection concentration limit (LOD) as low as 10-8 M and the enhancement factor (EF) up to 104 was found. The intercalated sample shows good uniformity as a SERS substrate, and the relative standard deviation (RSD) is as low as 14.14%. The SERS substrate still maintains a good enhancement effect after 21 days, showing excellent atmospheric stability. Furthermore, we demonstrate intercalation as a feasible way to improve the SERS of thick graphite and MoS2, which shows that the local intercalation method could be a universal method to design micro SERS platform on vdW two dimensional (2D) materials.