ELECTROLYTIC EFFECT ON GROWTH OF GRAPHENE QUANTUM DOTS VIA ELECTROCHEMICAL PROCESS

Author(s):  
RANSAN PANYATHIP ◽  
THANAKRIT SINTIAM ◽  
SORAWIT WEERAPONG ◽  
ATHIPONG NGAMJARUROJANA ◽  
PISIST KUMNORKAEW ◽  
...  

Quantum dots (QDs) are materials grown in confined dimension also known as 0D materials. QDs can be synthesized in many shapes and forms through various methods making the materials extremely versatile and can be fine-tuned for appropriate applications. Among the potentially scalable methods, Electrochemical process is considered as one of the top-down approaches with the highest potential for scalability and easy-to-process methodology while electrolyte and pH level can play various important roles on the final product. In this work, we grew and studied the effect of electrolytic solution in the growth of graphene quantum dots (GQDs) in colloidal forms using cheap graphite as precursor in KCl and NaOH as electrolytes in various concentrations. It can be inferred from our results that when KCl and NaOH were used in combination with citric acid, the optoelectrical properties and hydrodynamic properties of the resulting growth can be fine-tuned to match the required applications. [Formula: see text] electronics excitation was identified with small tunability of 487–500[Formula: see text]nm wavelength while the hydrodynamic size varied from 80–140[Formula: see text]nm with resulting pH range from 3.0–9.5 adjustable to appropriate applications, while the TEM results showed physical particle size of 1.7–3.7[Formula: see text]nm.

2021 ◽  
Vol 13 (9) ◽  
pp. 5273
Author(s):  
Yanpeng Zhang ◽  
Junjie Qi ◽  
Mengying Li ◽  
Dong Gao ◽  
Chengfen Xing

Graphene quantum dots (GQDs) have been successfully used as a highly sensitive probe for the sensing of formaldehyde (HCHO) in an aqueous solution. Through static quenching, the probe utilizes the interaction between HCHO and GQDs to trigger the “turn off” fluorescence response, and has good selectivity. The probe can detect HCHO in a pure aqueous solution, and it also can still detect HCHO in a complex environment with a pH range from 4 to 10. The concentration of HCHO and the fluorescence intensity of GQDs show a good linear relationship within the range of HCHO of 0–1 μg/mL, which was much more sensitive than previous reports. The limit of HCHO detection by GQDs is about 0.0515 μg/mL. In addition, we successfully applied it to the actual food inspection. It is proved to be a selective, sensitive and visualized method to check whether the concentration of HCHO in the foods exceeds the regulatory limit, which presents a potential application in food safety testing.


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.


2016 ◽  
Vol 31 (4) ◽  
pp. 337 ◽  
Author(s):  
SUN Xiao-Dan ◽  
LIU Zhong-Qun ◽  
YAN Hao

2014 ◽  
Vol 35 (4) ◽  
pp. 372
Author(s):  
Yong-qiang MA ◽  
Zhen-guo WANG ◽  
Xue-li GOU ◽  
Na LI ◽  
Ya-qiang FENG ◽  
...  

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