Graphene quantum dot

Graphene quantum dots (GQDs) represent single-layer to tens of layers of graphene of a size less than 30 nm. Due to its exceptional properties such as low toxicity, stable photoluminescence, chemical stability and pronounced quantum confinement effect, GQDs are considered as a novel material for biological, opto-electronics, energy and environmental applications.

Properties

The graphene quantum dot (GQD) is becoming an advanced multifunctional material for its unique optical, electronic,^[1] spin,^[2] and photoelectric properties induced by the quantum confinement effect and edge effect. GQDs are fragments limited in size, or domains, of a single-layer two-dimensional graphene crystal. Spectral studies have found that in almost all cases, GQDs are not single-layer graphene domains, but multi-layer formations containing up to 10 layers of reduced graphene oxide (rGO) from 10 to 60 nm in size.

Preparation

Presently, several techniques have been developed to prepare GQDs; these techniques mainly include electron beam lithography, chemical synthesis, electrochemical preparation, graphene oxide (GO) reduction, C60 catalytic transformation, the microwave assisted hydrothermal method (MAH),^[3][4] the Soft-Template method,^[5] the hydrothermal method,^[6][7][8] and the ultrasonic exfoliation method.^[9]

Application

GQDs have various important applications in bioimaging, drug delivery,^[10] LEDs lighter converters, photodetectors, OPV solar cells, and fluorescent material, biosensors fabrication.

References

1. Ritter, Kyle A.; Lyding, Joseph W. (15 February 2009). "The influence of edge structure on the electronic properties of graphene quantum dots and nanoribbons". Nature Materials. 8 (3): 235–242. doi:10.1038/nmat2378.
2. Güçlü, A. D.; Potasz, P.; Hawrylak, P. (25 July 2011). "Electric-field controlled spin in bilayer triangular graphene quantum dots". Physical Review B. 84 (3). doi:10.1103/PhysRevB.84.035425.
3. Tang, Libin; Ji, Rongbin; Cao, Xiangke; Lin, Jingyu; Jiang, Hongxing; Li, Xueming; Teng, Kar Seng; Luk, Chi Man; Zeng, Songjun; Hao, Jianhua; Lau, Shu Ping (2014). "Deep Ultraviolet Photoluminescence of Water-Soluble Self-Passivated Graphene Quantum Dots". ACS Nano. 8 (6): 6312–6320. doi:10.1021/nn300760g.
4. Tang, Libin; Ji, Rongbin; Li, Xueming; Bai, Gongxun; Liu, Chao Ping; Hao, Jianhua; Lin, Jingyu; Jiang, Hongxing; Teng, Kar Seng; Yang, Zhibin; Lau, Shu Ping (2012). "Deep Ultraviolet to Near-Infrared Emission and Photoresponse in Layered N-Doped Graphene Quantum Dots". ACS Nano. 6 (6): 5102–5110. doi:10.1021/nn501796r.
5. Tang, Libin; Ji, Rongbin; Li, Xueming; Teng, Kar Seng; Lau, Shu Ping (2013). "Size-Dependent Structural and Optical Characteristics of Glucose-Derived Graphene Quantum Dots". Particle & Particle Systems Characterization. 30 (6): 523–531. doi:10.1002/ppsc.201200131.
6. Li, Xueming; Lau, Shu Ping; Tang, Libin; Ji, Rongbin; Yang, Peizhi (2013). "Multicolour Light emission from chlorine-doped graphene quantum dots". J. Mater. Chem. C. 1: 7308–7313. doi:10.1039/C3TC31473A.
7. Li, Lingling; Wu, Gehui; Yang, Guohai; Peng, Juan; Zhao, Jianwei; Zhu, Jun-Jie (2013). "Focusing on luminescent graphene quantum dots: current status and future perspectives". Nanoscale. 5 (10): 4015. doi:10.1039/C3NR33849E.
8. Li, Xueming; Lau, Shu Ping; Tang, Libin; Ji, Rongbin; Yang, Peizhi (2014). "Sulphur Doping: A Facile Approach to Tune the Electronic Structure and Optical Properties of Graphene Quantum Dots". Nanoscale. 6: 5323–5328. doi:10.1039/C4NR00693C.
9. Zhao, Jianhong; Tang*, Libin; Xiang*, Jinzhong; Ji*, Rongbin; Yuan, Jun; Zhao, Jun; Yu, Ruiyun; Tai, Yunjian; Song, Liyuan (2014). "Chlorine Dopted Graphene Quantum Dots: Preparation, Properties, and Photovoltaic Detectors". Applied Physics Letters. 105: 111116. doi:10.1063/1.4896278.
10. Thakur, M. et al., 2016. Milk-derived multi-fluorescent graphene quantum dot-based cancer theranostic system. Materials Science and Engineering: C, 67, pp.468–477. Available at: http://linkinghub.elsevier.com/retrieve/pii/S0928493116304313.