Transient nature of graphene quantum dot formation via a hydrothermal reaction

RSC Advances Volume 4 Issue 99 Page 55709-55715 published_at 2014-10-21
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Title ( eng )
Transient nature of graphene quantum dot formation via a hydrothermal reaction
Creator
Iwasaki Hideharu
Aishima Kana
Iskandar Ferry
Wang Wei-Ning
Takimiya Kazuo
Source Title
RSC Advances
Volume 4
Issue 99
Start Page 55709
End Page 55715
Abstract
A facile, economic and environmentally friendly one-step approach for the preparation of highly luminescent graphene quantum dots (GQDs) was developed using a hydrothermal reaction between citric acid and urea. Unlike previous reports, we focused on the effect of the transient nature of GQD formation on the photoluminescence (PL) properties and molecular structure changes of the products. We found that the GQDs have an optimum reaction time and require an effective precursor to achieve excellent luminescent properties. The PL, ultraviolet-visible (UV-vis) absorption, zeta potential, and nuclear magnetic resonance (NMR) analyses of the GQDs prepared at various reaction times revealed that the molecular structures responsible for the luminescence of the GQDs are aggregates or condensation products of citric acid amides. We found that urea addition to the precursor drastically enhances the PL intensity of the GQDs, and it is 40 times higher than those prepared using the pure citric acid precursor. Additionally, a GQDs–polyvinyl alcohol composite achieved an excellent quantum yield (QY) of 43.6%.
Descriptions
This work was supported by JSPS KAKENHI Grant numbers 26709061 and 24656413. We thank Dr Eishi Tanabe from the Hiroshima Prefectural Institute of Industrial Science and Technology for helping with TEM analyses, and Drs Naoya Tochio and Junichi Kakimura from Hiroshima University for NMR analyses.
Language
eng
Resource Type journal article
Publisher
Royal Society of Chemistry
Date of Issued 2014-10-21
Rights
This journal is © The Royal Society of Chemistry 2014.
Publish Type Version of Record
Access Rights open access
Source Identifier
[DOI] 10.1039/C4RA09159K
[DOI] https://doi.org/10.1039/C4RA09159K
[ISSN] 2046-2069