FIGURE 3.

The graphene-based substrates for surface-enhanced Raman scattering (SERS). (A) Schematic illustration of the graphene only substrates. (B) Raman spectra of Pc molecules on monolayer graphene and on a blank SiO₂/Si substrate (Ling et al., 2010). (C) Schematic of SERS enhancement from a crumpled graphene–Au nanoparticles hybrid structure (Leem et al., 2015). (D) Graphene-covered nanoparticles or nanohole arrays for SERS enhancement (Hao et al., 2012). (E) Graphene-covered Au nanovoid arrays (Zhu et al., 2013). (F) Graphene-separated metal nanostructure substrates (Zhao et al., 2017). (G) Schematic illustration of the SERS detection of DNA based on graphene (Duan et al., 2015). (H) Optical and Raman images of HeLa 229 cells. The scale bar is 10 µm (Zhang et al., 2015).