scholarly journals Tuning the Photoluminescence of Graphene Quantum Dots by Fluorination

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Yi Luo ◽  
Yongjie Xu ◽  
Ming Li ◽  
Lang Sun ◽  
Guanghui Hu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Gaseous Phase ◽  
Water Solubility ◽  
Graphene Quantum Dots ◽  
Blue Shift ◽  
Atomic Ratio ◽  
Heating Method ◽  
Pl Emission ◽  
Fluorinated Graphene

Fluorinated graphene quantum dots (F-GQDs) were prepared by mixing GQDs and XeF2 in a facile gaseous phase heating method. The F-GQDs with excellent water solubility have a F/C atomic ratio of 84.25% and a diameter of 2–6 nm. The photoluminescence (PL) properties of GQDs and F-GQDs were investigated systematically. The results showed that the PL emission of the F-GQDs exhibited an obvious blue-shift of 90 nm compared to that of the GQDs.

scholarly journals Hydrothermal Synthesis of Sb2S3Nanorods Using Iodine via Redox Mechanism

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Abdolali Alemi ◽  
Sang Woo Joo ◽  
Younes Hanifehpour ◽  
Aliakbar Khandar ◽  
Ali Morsali ◽  
...  
Keyword(s):  
Elemental Sulfur ◽  
Orthorhombic Phase ◽  
Blue Shift ◽  
Atomic Ratio ◽  
High Yield ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spectrometry Analysis ◽  
Pl Emission ◽  
First Time

Crystalline antimony sulfide (Sb2S3) with nanorods morphology was successfully prepared via hydrothermal method by the reaction of elemental sulfur, antimony, and iodine as starting materials with high yield at 180∘C for 24 h. Using oxidation reagent like iodine as an initiator of redox reaction to prepare Sb2S3is reported for first time. The powder X-ray diffraction pattern shows the Sb2S3crystals belong to the orthorhombic phase with calculated lattice parameters,a=1.120 nm,b=1.128 nm, andc=0.383 nm. The quantification of energy-dispersive X-ray spectrometry analysis peaks gives an atomic ratio of 2 : 3 for Sb : S. TEM and SEM studies reveal the appearance of the as-prepared Sb2S3is rodlike which is composed of nanorods with the typical width of 50–140 nm and length of up to 4 μm. The PL emission indicates that band gap of Sb2S3is around 2.50 ev, indicating a considerable blue shift relative to the bulk. A formation mechanism of Sb2S3nanostructure is proposed.

Resistive switching effects in fluorinated graphene films with graphene quantum dots enhanced by polyvinyl alcohol

2019 ◽  
Vol 30 (25) ◽  
pp. 255701 ◽  
Author(s):  
Artem I Ivanov ◽  
Nadezhda A Nebogatikova ◽  
Igor A Kotin ◽  
Svetlana A Smagulova ◽  
Irina V Antonova
Keyword(s):  
Quantum Dots ◽  
Polyvinyl Alcohol ◽  
Resistive Switching ◽  
Graphene Quantum Dots ◽  
Graphene Films ◽  
Fluorinated Graphene

Preparation of Doped Graphene Quantum Dots with Bright and Excitation-Independent Blue Fluorescence

2014 ◽  
Vol 950 ◽  
pp. 44-47 ◽  
Author(s):  
Hui Li ◽  
Hai Ping He ◽  
Zhi Zhen Ye
Keyword(s):  
Aqueous Solution ◽  
Quantum Dots ◽  
Graphene Oxide ◽  
Graphene Quantum Dots ◽  
Blue Fluorescence ◽  
Doped Graphene ◽  
Pl Emission ◽  
Bright Blue ◽  
Co Doped ◽  
Blue Photoluminescence

Highly bright-fluorescent N (nitrogen), S (sulfur) co-doped graphene quantum dots (GQDs) were synthesized through an modified hydrothermal method. The doped GQDs are smaller than 10 nm in size in average and stable in aqueous solution. Unlike many reports on graphene oxide (GO), the as-synthesized doped GQDs exhibit bright blue photoluminescence (PL) emission and the emission wavelength is excitation-independent. The intriguling results indicate that GQDs may have great potential in the optic and optoelectronic applications.

scholarly journals Applications of Graphene Quantum Dots in Biomedical Sensors

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1072 ◽  
Author(s):  
Bhargav D. Mansuriya ◽  
Zeynep Altintas
Keyword(s):  
Quantum Dots ◽  
Water Solubility ◽  
Graphene Quantum Dots ◽  
Biomedical Sensors ◽  
Sensor Performance ◽  
Ultralow Concentrations ◽  
Wide Range ◽  
Methods Of Synthesis ◽  
Photo Stability

Due to the proliferative cancer rates, cardiovascular diseases, neurodegenerative disorders, autoimmune diseases and a plethora of infections across the globe, it is essential to introduce strategies that can rapidly and specifically detect the ultralow concentrations of relevant biomarkers, pathogens, toxins and pharmaceuticals in biological matrices. Considering these pathophysiologies, various research works have become necessary to fabricate biosensors for their early diagnosis and treatment, using nanomaterials like quantum dots (QDs). These nanomaterials effectively ameliorate the sensor performance with respect to their reproducibility, selectivity as well as sensitivity. In particular, graphene quantum dots (GQDs), which are ideally graphene fragments of nanometer size, constitute discrete features such as acting as attractive fluorophores and excellent electro-catalysts owing to their photo-stability, water-solubility, biocompatibility, non-toxicity and lucrativeness that make them favorable candidates for a wide range of novel biomedical applications. Herein, we reviewed about 300 biomedical studies reported over the last five years which entail the state of art as well as some pioneering ideas with respect to the prominent role of GQDs, especially in the development of optical, electrochemical and photoelectrochemical biosensors. Additionally, we outline the ideal properties of GQDs, their eclectic methods of synthesis, and the general principle behind several biosensing techniques.

scholarly journals Manganese(ii) enhanced fluorescent nitrogen-doped graphene quantum dots: a facile and efficient synthesis and their applications for bioimaging and detection of Hg2+ ions

RSC Advances ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 5902-5911 ◽  
Author(s):  
Li Yang ◽  
Aimiao Qin ◽  
Shuoping Chen ◽  
Lei Liao ◽  
Jiangke Qin ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Water Solubility ◽  
Raw Materials ◽  
Graphene Quantum Dots ◽  
Hydrothermal Carbonization ◽  
One Pot ◽  
Nitrogen Doped ◽  
Manganese Ion ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

Manganese ion (Mn2+) bonded nitrogen-doped graphene quantum dots (Mn(ii)-NGQDs) with water solubility have been successfully synthesized by a simple, one-pot hydrothermal carbonization, using sodium citrate, glycine and manganese chloride as raw materials.

Synthesis and photoluminescence of fluorinated graphene quantum dots

2013 ◽  
Vol 102 (1) ◽  
pp. 013111 ◽  
Author(s):  
Qian Feng ◽  
Qingqi Cao ◽  
Ming Li ◽  
Fuchi Liu ◽  
Nujiang Tang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Fluorinated Graphene

A Theoretical Investigation on the Dimensions and Annealing Effects of InAs/GaAs Quantum Dots for Device Applications at High Bit-Rate Optical Transmission Window of 1.3-1.55 μm

2012 ◽  
Vol 584 ◽  
pp. 423-427
Author(s):  
K. Ghosh ◽  
Y. Naresh ◽  
N. Srichakradhar Reddy
Keyword(s):  
Quantum Dots ◽  
Optical Transmission ◽  
Blue Shift ◽  
Specific Device ◽  
Base Size ◽  
Annealing Effects ◽  
Device Applications ◽  
Transmission Window ◽  
High Bit Rate ◽  
Pl Emission

In this paper, we present theoretical model and computations for tuning the photoluminescence (PL) emission of InAs/GaAs quantum dots at 1.3 -1.55 μm by optimizing its height and base dimensions through quantum mechanical concepts. Simulation on the annealing induced compositional change in the QDs was carried out using Fick’s diffusion model. Results from our computation illustrated that lower base size of 10 nm and larger height QDs of 5.1 nm can be effectively utilized for extending the PL emission to longer wavelengths with minimal blue-shift on annealing. This highlights the potential of our model and computation to assist in precisely engineering the optical properties of QD materials for specific device applications.

scholarly journals Antioxidant Activity of Graphene Quantum Dots Prepared in Different Electrolyte Environments

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1708 ◽  
Author(s):  
Lin Zhao ◽  
Yingmin Wang ◽  
Yan Li
Keyword(s):  
Quantum Dots ◽  
Antioxidant Activity ◽  
Free Radicals ◽  
Water Solubility ◽  
Radical Scavenging Activity ◽  
Graphene Quantum Dots ◽  
Radical Scavenging ◽  
Effective Control ◽  
Antioxidant Mechanism ◽  
Scavenging Efficiency

Antioxidants can reduce or inhibit damage such as oxidative decay caused by elevated levels of free radicals. Therefore, pursuing antioxidants with excellent properties has attracted more and more attention. Graphene quantum dots (GQDs) are considered a promising material because of their good free radical scavenging activity, low toxicity, and excellent water solubility. However, their scavenging efficiency, antioxidant mechanism, and effective control methods need to be improved. Herein, in order to further reveal the antioxidant mechanism of GQDs, the role of electrolytes in improving the antioxidant activity of GQDs is explored. In addition, 1,1-diphenyl-2-picrazine (DPPH∙), hydroxyl (∙OH), and superoxide (∙O2−) free radicals are used to evaluate the antioxidant activity of the as-prepared GQDs. Combined with transmission electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and cyclic volt–ampere characteristic curves, the effects of an electrolytic environment on the surface functional groups, charge transfer capability, and defect states of GQDs are obtained. The antioxidant mechanism of GQDs and how to improve their antioxidant activity are further elucidated.

InAs/In0.15Ga0.85As1−xNx quantum dots for 1.5 μm laser applications

2005 ◽  
Vol 891 ◽  
Author(s):  
Mirja Richter ◽  
Benjamin Damilano ◽  
Jean Massies ◽  
Jean-Yves Duboz ◽  
Andreas D. Wieck
Keyword(s):  
Quantum Dots ◽  
Gaas Substrate ◽  
Molecular Beam ◽  
Annealing Temperature ◽  
Optimal Growth ◽  
Blue Shift ◽  
Laser Applications ◽  
Inas Quantum Dots ◽  
Pl Emission ◽  
Optimum Annealing Temperature

ABSTRACTSelf-assembled InAs quantum dots (QDs) on GaAs substrate encapsulated with In0.15Ga0.85As1−xNx (GINA) have been grown by solid source molecular beam epitaxy, using optimal growth temperatures and rates for each of the two layers. The photoluminescence (PL) intensity increases for annealed samples. The optimum annealing temperature depends on the nitrogen composition. InAs QDs overgrown with larger nitrogen mole fraction GINA show a smaller PL peak blue-shift after annealing. Intense and narrow PL emission in the 1.5 µm range is achieved for samples annealed at optimal temperature.

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