scholarly journals Green Preparation of High Yield Fluorescent Graphene Quantum Dots from Coal-Tar-Pitch by Mild Oxidation

Nanomaterials ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 844 ◽  
Author(s):  
Quanrun Liu ◽  
Jingjie Zhang ◽  
He He ◽  
Guangxu Huang ◽  
Baolin Xing ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Coal Tar ◽  
Graphene Quantum Dots ◽  
High Yield ◽  
Coal Tar Pitch ◽  
Narrow Size Distribution ◽  
Material Source ◽  
Graphene Layers ◽  
Mild Conditions ◽  
Simple Strategy

Coal tar pitch (CTP), a by-product of coking industry, has a unique molecule structure comprising an aromatic nucleus and several side chains bonding on this graphene-like nucleus, which is very similar to the structure of graphene quantum dots (GQDs). Based on this perception, we develop a facile approach to convert CTP to GQDs only by oxidation with hydrogen peroxide under mild conditions. One to three graphene layers, monodisperse GQDs with a narrow size distribution of 1.7 ± 0.4 nm, are obtained at high yield (more than 80 wt. %) from CTP. The as-produced GQDs are highly soluble and strongly fluorescent in aqueous solution. This simple strategy provides a feasible route towards the commercial synthesis of GQDs for its cheap material source, green reagent, mild condition, and high yield.

scholarly journals High yield synthesis of graphene quantum dots from biomass waste as a highly selective probe for Fe3+ sensing

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Aumber Abbas ◽  
Tanveer A. Tabish ◽  
Steve J. Bull ◽  
Tuti Mariana Lim ◽  
Anh N. Phan
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Low Cost ◽  
Graphene Quantum Dots ◽  
Cost Effective ◽  
Renewable Resource ◽  
Microwave Treatment ◽  
High Yield ◽  
Biomass Waste ◽  
Practical Applications

AbstractGraphene quantum dots (GQDs), a novel type of zero-dimensional fluorescent materials, have gained considerable attention owing to their unique optical properties, size and quantum confinement. However, their high cost and low yield remain open challenges for practical applications. In this work, a low cost, green and renewable biomass resource is utilised for the high yield synthesis of GQDs via microwave treatment. The synthesis approach involves oxidative cutting of short range ordered carbon derived from pyrolysis of biomass waste. The GQDs are successfully synthesised with a high yield of over 84%, the highest value reported to date for biomass derived GQDs. As prepared GQDs are highly hydrophilic and exhibit unique excitation independent photoluminescence emission, attributed to their single-emission fluorescence centre. As prepared GQDs are further modified by simple hydrothermal treatment and exhibit pronounced optical properties with a high quantum yield of 0.23. These modified GQDs are used for the highly selective and sensitive sensing of ferric ions (Fe3+). A sensitive sensor is prepared for the selective detection of Fe3+ ions with a detection limit of as low as 2.5 × 10–6 M. The utilisation of renewable resource along with facile microwave treatment paves the way to sustainable, high yield and cost-effective synthesis of GQDs for practical applications.

scholarly journals Facile synthesis of preformed mixed nano-carbon structure from low rank coal

2018 ◽  
Vol 36 (1) ◽  
pp. 14-20 ◽  
Author(s):  
B. Manoj ◽  
Ashlin M. Raj ◽  
George Thomas Chirayil
Keyword(s):  
Quantum Dots ◽  
Carbon Dots ◽  
Bituminous Coal ◽  
Graphene Quantum Dots ◽  
Energy Resource ◽  
Low Rank ◽  
Tem Analysis ◽  
Graphene Layers ◽  
Simple Chemical ◽  
Nano Carbon

Abstract Coal is a natural energy resource which is mainly used for energy production via combustion. Coal has nanocrystals embedded in it, formed during the coalification process, and is an ideal precursor for nano-carbon dots and diamonds. Herein, we report a facile top-down method to synthesise nanodots and diamonds of the size of 5 nm to 10 nm from three different types of coal by simple chemical leaching. TEM analysis revealed the formation of a mixture of carbon dots, graphene layers, and quantum dots in bituminous coal and sub-bituminous coal. Raman analysis confirmed the existence of synthesized nanodiamond and nano-carbon mixed phase with defects associated with it. It is concluded that graphene quantum dots, nanodiamonds, graphene sheets and carbon dots present in coal can be extracted by simple chemical treatment. These structures can be tuned to photoluminescent material for various optoelectronic applications or energy harvesting devices like super capacitors.

Coal tar pitch as natural carbon quantum dots decorated on TiO2 for visible light photodegradation of rhodamine B

Carbon ◽  
2019 ◽  
Vol 152 ◽  
pp. 284-294 ◽  
Author(s):  
Jingjie Zhang ◽  
Quanrun Liu ◽  
He He ◽  
Feng Shi ◽  
Guangxu Huang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Visible Light ◽  
Rhodamine B ◽  
Coal Tar ◽  
Carbon Quantum Dots ◽  
Coal Tar Pitch ◽  
Natural Carbon

scholarly journals A Novel Route to High-Quality Graphene Quantum Dots by Hydrogen-Assisted Pyrolysis of Silicon Carbide

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 277 ◽  
Author(s):  
Na Eun Lee ◽  
Sang Yoon Lee ◽  
Hyung San Lim ◽  
Sung Ho Yoo ◽  
Sung Oh Cho
Keyword(s):  
Quantum Dots ◽  
Silicon Carbide ◽  
Quantum Confinement ◽  
Graphene Quantum Dots ◽  
Simple Approach ◽  
Operating Conditions ◽  
High Quality ◽  
Graphene Layers ◽  
High Crystallinity ◽  
Effective Charge Transfer

Graphene quantum dots (GQDs) can be highly beneficial in various fields due to their unique properties, such as having an effective charge transfer and quantum confinement. However, defects on GQDs hinder these properties, and only a few studies have reported fabricating high-quality GQDs with high crystallinity and few impurities. In this study, we present a novel yet simple approach to synthesizing high-quality GQDs that involves annealing silicon carbide (SiC) under low vacuum while introducing hydrogen (H) etching gas; no harmful chemicals are required in the process. The fabricated GQDs are composed of a few graphene layers and possess high crystallinity, few defects and high purity, while being free from oxygen functional groups. The edges of the GQDs are hydrogen-terminated. High-quality GQDs form on the etched SiC when the etching rates of Si and C atoms are monitored. The size of the fabricated GQDs and the surface morphology of SiC can be altered by changing the operating conditions. Collectively, a novel route to high-quality GQDs will be highly applicable in fields involving sensors and detectors.

High-yield synthesis of graphene quantum dots with strong green photoluminescence

RSC Advances ◽  
2014 ◽  
Vol 4 (91) ◽  
pp. 50141-50144 ◽  
Author(s):  
J. Gu ◽  
M. J. Hu ◽  
Q. Q. Guo ◽  
Z. F. Ding ◽  
X. L. Sun ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Yield ◽  
Graphene Quantum Dots ◽  
High Yield ◽  
Photoluminescence Emission ◽  
Emission Performance ◽  
Fluorescent Quantum Yield ◽  
Green Photoluminescence

The obtained GQDs have high fluorescent quantum yield (FL QY = 44.3%) and excitation-independent photoluminescence emission performance.

One-step and high yield simultaneous preparation of single- and multi-layer graphene quantum dots from CX-72 carbon black

2012 ◽  
Vol 22 (18) ◽  
pp. 8764 ◽  
Author(s):  
Yongqiang Dong ◽  
Congqiang Chen ◽  
Xinting Zheng ◽  
Lili Gao ◽  
Zhiming Cui ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Carbon Black ◽  
Graphene Quantum Dots ◽  
High Yield ◽  
Layer Graphene ◽  
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