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Anomalous Fluorescence Enhancement and Fluorescence Quenching of Graphene Quantum Dots by Single Walled Carbon Nanotubes

Abstract

We explore the mechanism of fluorescence enhancement and fluorescence quenching effect of single walled carbon nanotubes (SWCNTs) on highly fluorescent graphene quantum dot (GQDs) over a wide range of concentrations of SWCNTs. At very low concentrations of SWCNTs, fluorescence intensity of GQDs is enhanced, while at higher concentrations, systematic quenching of fluorescence is observed. The nature of Stern–Volmer plot for the later case was found to be non-linear indicating combined effect of dynamic and static quenching. The contribution of dynamic quenching component was assessed through the fluorescence lifetime measurements. The contribution of static quenching is confirmed from the red shift of fluorescence spectra of the GQDs after addition of SWCNTs. The fluorescence intensity is first enhanced at very low concentration due to improved dispersion and higher absorption by GQDs, while at higher concentration the fluorescence of GQDs is quenched due to the complex formation and associated reduction of the radiative sites of GQDs, which is confirmed from time resolved fluorescence measurements. Laser confocal microscopy imaging provides direct evidence of the enhancement and quenching of fluorescence at low and high concentration of SWCNTs, respectively. This study provides an important insight in tuning the fluorescence of GQDs and understanding the interaction between GQDs and different CNTs, which is important for bio-imaging and drug delivery applications.

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Publication details

The article was received on 13 Oct 2017, accepted on 10 Jan 2018 and first published on 10 Jan 2018


Article type: Paper
DOI: 10.1039/C7CP06994D
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    Anomalous Fluorescence Enhancement and Fluorescence Quenching of Graphene Quantum Dots by Single Walled Carbon Nanotubes

    R. Das, G. Rajender and P. K. Giri, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C7CP06994D

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