Synthesis of graphene quantum dots and Nitrogen-doped graphene quantum dots: Raman characterization and their optical properties

Abstract

In this report we present completely new results on the improvement of the method of producing graphene quantum dots (GQDs) and nitrogen-doped graphene quantum dots (GQD-N), by using the microwave with different powers and durations, from citric acid and urea. This is a new and unprecedented method of fabrication. The use of microwaves has allowed ultra-fast fabrication of GQDs and nitrogen doped GQDs. These GQDs had their characteristics identified by Raman scattering spectra for the characteristic C-C graphene vibration mode (G-peak) and
defects of GQDs (D-peak). The absorption spectra of GQDs samples were fabricated under different conditions, with an expectation of different sizes, to be compared and analyzed. These
absorption spectra were also compared with those of the GQD-N produced under the same conditions. The absorption  echanism of GQDs and GQD-N is presented in detail. Measurements of the photoluminescence spectra in GQDs and GQD-N have also been recorded and analyzed. The fluorescence mechanism will be presented, explained, and compared with that of authors in other international publications. Some of the TEM and HR-TEM images of these two samples were also presented to confirm the shape, size and in-plane spacing lattice of the GQD structure.