Is the Chain of Oxidation and Reduction Process Reversible in Luminescent Graphene Quantum Dots?

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Title
Is the Chain of Oxidation and Reduction Process Reversible in Luminescent Graphene Quantum Dots?
Author(s)
Jang, MH; Hyun Dong Ha; Eui-Sup Lee; Liu, F; Yong-Hyun Kim; Seo, TS; Cho, YH
Publication Date
2015-08
Journal
SMALL, v.11, no.31, pp.3773 - 3781
Publisher
WILEY-V C H VERLAG GMBH
Abstract
Graphene-based quantum dots (QDs) have received a tremendous amount of attention as a new type of light-emitting materials. However, their luminescence origins remain controversial due to extrinsic states of the impurities and disorder structures. Especially, the function of oxygen-contents should be understood and controlled as a crucial element for tuning the optical properties of graphene-based QDs. Herein, a series of graphene oxide QDs (GOQDs) with different amounts of oxygen-contents are first synthesized via a direct oxidation route of graphite nanoparticle and thoroughly compared with a series of reduced GOQDs (rGOQDs) prepared by the conventional chemical reduction. Irreversible emission and different carrier dynamics are observed between the GOQDs and rGOQDs, although both routes show a similar tendency with regard to the variation of oxygen-functional components. Their luminescence mechanisms are closely associated with different atomic structures. The mechanism for the rGOQDs can be associated with a formation of small sp2 nanodomains as luminescent centers, whereas those of GOQDs may be composed of oxygen-islands with difference sizes depending on oxidation conditions surrounded by a large area of sp2 bonding. Important insights for understanding the optical properties of graphene-based QDs and how they are affected by oxygen-functional groups are shown. Graphene oxide quantum dots (GOQDs) are first synthesized without a reduction process. These GOQDs show clear multicolor emissions depending on the number of oxygen functional groups under single-wavelength excitation. Also, it is demonstrated that the optical properties of reduced GOQDs do not match those of GOQDs, corresponding to irreversible optical origins in oxidation and reduction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
URI
https://pr.ibs.re.kr/handle/8788114/4854
ISSN
1613-6810
Appears in Collections:
Center for Nanomaterials and Chemical Reactions(나노물질 및 화학반응 연구단) > Journal Papers (저널논문)
Files in This Item:
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