Comparison of the activity of graphene oxide and CVD graphene-based substrates to be used in surface enhanced raman spectroscopy applications

Surface-enhanced Raman spectroscopy has been a popular topic of scientific discussion since its invention, as it is an effective analytical characterization method for the detection of biological and chemical molecules. Also, the selection of a suitable SERS substrate is always a challenge for specific molecules and trace amounts. To achieve consistent and reliable signal development, the fabrication process of the SERS substrate is important. In this work, two different types of graphene-based SERS substrates were fabricated and a comparison was made between these substrates. Rhodamine 6G (R6G) was used as the probe molecule for this study. Our graphene (CVDG) SERS substrates prepared by chemical vapour deposition method achieved a perfect limit of detection (LOD) of 10-13 M. To date, the value of 10-13 M is the lowest concentration value ever achieved for the graphene-based SERS substrates, growth for R6G molecules. These results show that our CVDG SERS substrate is quite accurate. When a substrate that is transparent, flexible and with a large surface area is desired, it corresponds to CVD graphene (CVDG) SERS substrates, on the other hand, for the applications of dust, colloid and thin film SERS modified graphene oxide (MGO) may be more suitable. MGO showed better signal development than the reference substrates CVDG and SiO2 in high concentrations of R6G solution. The differences between the substrates in terms of their SERS activities were discussed in detail from the aspect of chemical, electrical, optical properties and surface morphology of CVDG and MGO. It is crucial to understand the development of enhancement process activities of non-resonant materials for the new generation of Raman spectroscopy instruments. The materials we have produced can be used as reliable SERS substrates for the detection of certain sensitive molecules and can also be modified with other resonant nanoparticles.