Controllable growth of 2D ReS2 flakes and their surface Raman enhancement effects

Two-dimensional (2D) ReS2 has received widespread attention because of its unique anisotropic properties, weak interlayer interactions and broad application prospects. Therefore, the controllable and repeatable growth of 2D ReS2 flakes is very important for studying their properties and practical applications. In this work, 2D single-crystalline ReS2 flakes with different layer numbers were synthesized on mica substrates using chemical vapor deposition (CVD) by adjusting the distance between the mica substrate and Re source, and the growth mechanism was further discussed. The fluorescence quenching effect and surface-enhanced Raman scattering (SERS) effect of 2D ReS2 flakes were investigated using rhodamine B (RhB), crystal violet (CV) and malachite green (MG) dye molecules as Raman probes. The results show that the fluorescence quenching effect and SERS effect of 2D ReS2 flakes are enhanced with decreasing layer number. The lowest detection limits on monolayer ReS2 flake substrates are 10−10 M, 10−9 M and 10−8 M for RhB, CV and MG under 532 nm laser excitation, respectively. 2D ReS2 flakes used as a sensitive SERS-active substrate have excellent uniformity and stability. The surface Raman enhancement mechanism of 2D ReS2 flakes was discussed.