Investigation of the Microstructures of Graphene Quantum Dots (GQDs) by Surface-Enhanced Raman Spectroscopy
The Beijing Key Laboratory for Nano-photonics and Nano-structure, Department of Physics, Capital Normal University, Beijing 100048, China
*
Author to whom correspondence should be addressed.
Nanomaterials 2018, 8(10), 864; https://doi.org/10.3390/nano8100864
Received: 21 September 2018
/
Revised: 17 October 2018
/
Accepted: 19 October 2018
/
Published: 22 October 2018
(This article belongs to the Special Issue Surface Enhanced Raman Spectroscopy in Nano-World)
Photoluminescence (PL) is the most significant feature of graphene quantum dots (GQDs). However, the PL mechanism in GQDs has been debated due to the fact that the microstructures, such as edge and in-plane defects that are critical for PL emission, have not been convincingly identified due to the lack of effective detection methods. Conventional measures such as high-resolution transmission electron microscopy and infrared spectroscopy only show some localized lattice fringes of GQDs and the structures of some substituents, which have little significance in terms of thoroughly understanding the PL effect. Here, surface-enhanced Raman spectroscopy (SERS) was introduced as a highly sensitive surface technique to study the microstructures of GQDs. Pure GQDs were prepared by laser ablating and cutting highly oriented pyrolytic graphite (HOPG) parallel to the graphite layers. Consequently, abundant SERS signals of the GQDs were obtained on an Ag electrode in an electrochemical environment for the first time. The results convincingly and experimentally characterized the typical and detailed features of GQDs, such as the crystallinity of sp2 hexagons, the quantum confinement effect, various defects on the edges, sp3-like defects and disorders on the basal planes, and passivated structures on the periphery and surface of the GQDs. This work demonstrates that SERS is thus by far the most effective technique for probing the microstructures of GQDs.
View Full-Text
Keywords:
graphene quantum dots; surface-enhanced Raman spectroscopy; photoluminescence; laser ablation; passivation
▼
Show Figures
Graphical abstract
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
MDPI and ACS Style
Wu, J.; Wang, P.; Wang, F.; Fang, Y. Investigation of the Microstructures of Graphene Quantum Dots (GQDs) by Surface-Enhanced Raman Spectroscopy. Nanomaterials 2018, 8, 864. https://doi.org/10.3390/nano8100864
AMA Style
Wu J, Wang P, Wang F, Fang Y. Investigation of the Microstructures of Graphene Quantum Dots (GQDs) by Surface-Enhanced Raman Spectroscopy. Nanomaterials. 2018; 8(10):864. https://doi.org/10.3390/nano8100864
Chicago/Turabian StyleWu, Junxiao, Peijie Wang, Fuhe Wang, and Yan Fang. 2018. "Investigation of the Microstructures of Graphene Quantum Dots (GQDs) by Surface-Enhanced Raman Spectroscopy" Nanomaterials 8, no. 10: 864. https://doi.org/10.3390/nano8100864
Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.
