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Nano Research

Article Title

Surface plasmon enhancement of photoluminescence in photo-chemically synthesized graphene quantum dot and Au nanosphere

Keywords

graphene quantum dot, gold, nanosphere, photoluminescence, UV irradiation

Abstract

Graphene quantum dots (GQDs) are promising candidates for potentialapplications such as novel optoelectronic devices and bio-imaging. However,insufficient light absorption to exhibit their intriguing characteristics. Thestrong confinement of light caused by the Au nanoparticles as an antennacan considerably boost the light absorption. With the assistance of ultravioletirradiation, we prepared bluish-green luminescent nanospheres by the hybridizationof GQD and Au nanoparticles (GQD/Au). These nanospheres showed aphotoluminescence quantum yield of up to 26.9%. The GQD/Au nanosphereswere synthesized using a solution of GQDs and HAuCl4 by a photochemicalmethod with the reduction of GQDs and the formation of metallic Au. TheGQDs and Au nanoparticles self-assembled and aggregated into nanospheresvia aurophilicity and hydrogen bonding interactions. The average size of theGQD/Au nanospheres was found to be in the range of 150–170 nm, which ismuch larger than that of the pristine GQDs (4–7 nm). The GQD/Au nanospheresexhibited an absorption band at 541 nm, which indicates the presence of Au inthe nanospheres. The typical absorbance features of GQDs were observed near236 and 303 nm. The photoluminescence characteristics were investigated usingthe excitation and emission spectra. The GQD/Au nanospheres exhibited twoemission peaks at 468 and 529 nm in the visible range. The green fluorescentpeak located at 529 nm was newly generated by the hybridization. The GQD/Aunanospheres showed an emission efficiency which was two times more thanthat of the intrinsic GQDs. The reason for this increase was the surface plasmonresonance from the Au particles, which improved the fluorescence property ofthe resulting nanospheres. These nanospheres can be perceived as outstandingcandidates for applications such as displays, optoelectronic devices, and imagingof the biological samples with high emission intensity.

Graphical Abstract

Publisher

Tsinghua University Press

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