scholarly journals Surface Enhanced Raman Scattering in Graphene Quantum Dots Grown via Electrochemical Process

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5484
Author(s):  
Rangsan Panyathip ◽  
Sukrit Sucharitakul ◽  
Surachet Phaduangdhitidhada ◽  
Athipong Ngamjarurojana ◽  
Pisist Kumnorkaew ◽  
...  

Graphene Quantum dots (GQDs) are used as a surface-enhanced Raman substrate for detecting target molecules with large specific surface areas and more accessible edges to enhance the signal of target molecules. The electrochemical process is used to synthesize GQDs in the solution-based process from which the SERS signals were obtained from GQDs Raman spectra. In this work, GQDs were grown via the electrochemical process with citric acid and potassium chloride (KCl) electrolyte solution to obtain GQDs in a colloidal solution-based format. Then, GQDs were characterized by transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy, respectively. From the results, SERS signals had observed via GQDs spectra through the Raman spectra at D (1326 cm−1) and G (1584 cm−1), in which D intensity is defined as the presence of defects on GQDs and G is the sp2 orbital of carbon signal. The increasing concentration of KCl in the electrolyte solution for 0.15M to 0.60M demonstrated the increment of Raman intensity at the D peak of GQDs up to 100 over the D peak of graphite. This result reveals the potential feasibility of GQDs as SERS applications compared to graphite signals.

2017 ◽  
Vol 5 (44) ◽  
pp. 11411-11415 ◽  
Author(s):  
Lixia Qin ◽  
Jiefei Liu ◽  
Shi-Zhao Kang ◽  
Guodong Li ◽  
Xiangqing Li

Gold nanoparticles of various sizes were facially assembled with a glycine derivative and graphene quantum dots, respectively. The obtained gold-based composites showed a strong dependence of fluorescence and surface enhanced Raman scattering response on the size of the AuNPs.


Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 864 ◽  
Author(s):  
Junxiao Wu ◽  
Peijie Wang ◽  
Fuhe Wang ◽  
Yan Fang

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.


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