Photoluminescence enhancement of single-layer graphene quantum dots by the surface plasmon resonance of Au nanocubes

Highly photoluminescent single-layer graphene quantum dots around Au nanocubes (SLGQDs/Au) were synthesized using a simple method. The SLGQDs were synthesized using a low-cost hydrothermal method from glucose as a precursor. The atomic force microscopy analysis proved that the average thickness of the GQDs is lower than 4 angstrom, meaning that the GQDs are single-layer dots. The novel cubic shape of the SLGQDs/Au nanocomposites was confirmed by field-emission scanning electron microscopy and Transmission electron microscopy. Structural characterization was performed by X-ray diffraction, energy-dispersive X-ray spectroscopy and Raman spectroscopy. Photoluminescence (PL) spectroscopy revealed that the obtained SLGQDs/Au nanocomposite has a higher PL emission peak intensity than that of the SLGQDs, which is due to the surface plasmon resonance of Au nanocubes at 530 nm, revealed in the UV-Vis absorption spectra. Finally, the effect of Au concentration on the PL emission peak intensity of the SLGQDs was studied, and the quantum yield of the optimum sample was measured and discussed.