Surface enhancement Raman spectroscopy of CVD graphene and graphene oxide

Abstract

SERS has been of interest as an influential analytical characterization method for scientific studies to detect chemical and biological molecules. The selection of suitable SERS substrates is a major challenge for specific detection of molecules. Here, two different types of graphene-based SERS substrates were prepared and their SERS activities were compared. Our chemical vapor-deposited graphene (CVDG) SERS substrates showed an excellent limit of detection of 10−13 M. 10−13 M is the lowest concentration achieved so far in the as grown graphene-based SERS substrates without the use of noble metal or other materials for R6G molecules. When a flexible and transparent SERS substrate with a large surface area is desired, substrates made of CVDG SERS substrates are more suitable, while modified graphene oxide (MGO) may be preferred in powder, colloid and thin film SERS applications. MGO showed better signal enhancement compared to CVDG and SiO2 reference substrates in high concentration R6G solution. The differences between the SERS activities of the substrates were discussed in detail in terms of the differences in the chemical, electrical, optical, and surface properties of CVDG and MGO. Understanding the enhancement activities of non-resonant graphene-based SERS materials is critical for the next generation of Raman spectrometer instruments.