scholarly journals Graphene Quantum Dots with High Yield and High Quality Synthesized from Low Cost Precursor of Aphanitic Graphite

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 375 ◽  
Author(s):  
Shuling Shen ◽  
Junjie Wang ◽  
Zhujun Wu ◽  
Zheng Du ◽  
Zhihong Tang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Low Cost ◽  
Graphene Quantum Dots ◽  
High Strength ◽  
High Yield ◽  
Average Thickness ◽  
High Quality ◽  
Graphene Oxide Quantum Dots ◽  
2D Nanosheets ◽  
First Time

It is difficult to keep the balance of high quality and high yield for graphene quantum dots (GQDs). Because the quality is uncontrollable during cutting large 2D nanosheets to small 0D nanodots by top-down methods and the yield is low for GQDs with high quality obtained from bottom-up strategy. Here, aphanitic graphite (AG), a low-cost graphite contains a large amount of small graphite nanocrystals with size of about 10 nm is used as the precursor of graphene oxide quantum dots (GO-QDs) for the first time. GO-QDs with high yield and high quality were successfully obtained directly by liquid phase exfoliating AG without high strength cutting. The yield of these GO-QDs can reach up to 40 wt. %, much higher than that obtained from flake graphite (FG) precursor (less than 10 wt. %). The size of GO-QDs can be controlled in 2–10 nm. The average thickness of GO-QDs is about 3 nm, less than 3 layer of graphene sheet. Graphene quantum dots (GQDs) with different surface properties can be easily obtained by simple hydrothermal treatment of GO-QDs, which can be used as highly efficient fluorescent probe. Developing AG as precursor for GQDs offers a way to produce GQDs in a low-cost, highly effective and scalable manner.

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 Graphene Quantum Dots Open Up New Prospects for Interfacial Modifying in Graphene/Silicon Schottky Barrier Solar Cell

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Chao Geng ◽  
Xiuhua Chen ◽  
Shaoyuan Li ◽  
Zhao Ding ◽  
Wenhui Ma ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Particle Size ◽  
Schottky Barrier ◽  
Low Cost ◽  
Graphene Quantum Dots ◽  
Separation Processes ◽  
Band Bending ◽  
Carrier Recombination ◽  
Photovoltaic Applications ◽  
Graphene Oxide Quantum Dots

Graphene/silicon (Gr/Si) Schottky barrier solar cells (SBSCs) are attractive for harvesting solar energy and have been gaining grounds for its low-cost solution-processing. The interfacial barrier between graphene and silicon facilitates the reducing excessive carrier recombination while accelerating the separation processes of photo-generated carriers at the interface, which empowers the performance of Gr/Si SBSCs. However, the difficulty to control the interface thickness prevents its application. Here, we introduce the graphene oxide quantum dots (GOQDs) as a unique interfacial modulation species with tunable thickness by controlling the GOQDs particle size. The power conversion efficiency (PCE) of 13.67% for Gr/Si-based SBSC with outstanding stability in the air is obtained with the optimal barrier thickness (26 nm) and particle size (4.15 nm) of GOQDs. The GOQDs in Gr/Si-based SBSCs provide the extra band bending which further enhances the PCE for its photovoltaic applications.

scholarly journals Design of Low-Cost and High-Strength Titanium Alloys Using Pseudo-Spinodal Mechanism through Diffusion Couple Technology and CALPHAD

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2910
Author(s):  
Chaoyi Ding ◽  
Chun Liu ◽  
Ligang Zhang ◽  
Di Wu ◽  
Libin Liu
Keyword(s):  
Diffusion Couple ◽  
Titanium Alloys ◽  
High Throughput ◽  
Volume Fraction ◽  
Raw Materials ◽  
Low Cost ◽  
High Strength ◽  
High Yield ◽  
Α Phase ◽  
Cr System

The high cost of development and raw materials have been obstacles to the widespread use of titanium alloys. In the present study, the high-throughput experimental method of diffusion couple combined with CALPHAD calculation was used to design and prepare the low-cost and high-strength Ti-Al-Cr system titanium alloy. The results showed that ultra-fine α phase was obtained in Ti-6Al-10.9Cr alloy designed through the pseudo-spinodal mechanism, and it has a high yield strength of 1437 ± 7 MPa. Furthermore, application of the 3D strength model of Ti-6Al-xCr alloy showed that the strength of the alloy depended on the volume fraction and thickness of the α phase. The large number of α/β interfaces produced by ultra-fine α phase greatly improved the strength of the alloy but limited its ductility. Thus, we have demonstrated that the pseudo-spinodal mechanism combined with high-throughput diffusion couple technology and CALPHAD was an efficient method to design low-cost and high-strength titanium alloys.

scholarly journals A Novel and Efficient High-Yield Method for Preparing Bacterial Ghosts

Toxins ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 420
Author(s):  
Yi Ma ◽  
Liu Cui ◽  
Meng Wang ◽  
Qiuli Sun ◽  
Kaisheng Liu ◽  
...  
Keyword(s):  
Large Scale ◽  
Expression System ◽  
High Yield ◽  
Wild Type ◽  
High Quality ◽  
Efficient Protection ◽  
Bacterial Ghosts ◽  
Cell Envelopes ◽  
Extracellular Structures ◽  
First Time

Bacterial ghosts (BGs) are empty cell envelopes possessing native extracellular structures without a cytoplasm and genetic materials. BGs are proposed to have significant prospects in biomedical research as vaccines or delivery carriers. The applications of BGs are often limited by inefficient bacterial lysis and a low yield. To solve these problems, we compared the lysis efficiency of the wild-type protein E (EW) from phage ΦX174 and the screened mutant protein E (EM) in the Escherichia coli BL21(DE3) strain. The results show that the lysis efficiency mediated by protein EM was improved. The implementation of the pLysS plasmid allowed nearly 100% lysis efficiency, with a high initial cell density as high as OD600 = 2.0, which was higher compared to the commonly used BG preparation method. The results of Western blot analysis and immunofluorescence indicate that the expression level of protein EM was significantly higher than that of the non-pLysS plasmid. High-quality BGs were observed by SEM and TEM. To verify the applicability of this method in other bacteria, the T7 RNA polymerase expression system was successfully constructed in Salmonella enterica (S. Enterica, SE). A pET vector containing EM and pLysS were introduced to obtain high-quality SE ghosts which could provide efficient protection for humans and animals. This paper describes a novel and commonly used method to produce high-quality BGs on a large scale for the first time.

Ball-Milling Graphite Used for Synthesis of Biocompatible Blue Luminescent Graphene Quantum Dots

2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Zhou J ◽  
◽  
Dong Y ◽  
Ma Y ◽  
Zhang T ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Ball Milling ◽  
Graphene Quantum Dots ◽  
Raw Material ◽  
Hydroxyl Groups ◽  
High Quality ◽  
Widespread Application ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

Graphene Quantum Dots (GQDs) have been prepared by oxidationhydrothermal reaction, using ball-milling graphite as the starting materials. The prepared GQDs are endowed with excellent luminescence properties, with the optimum emission of 320nm. Blue photoluminescent emitted from the GQDs under ultraviolet light. The GQDs are ~3nm in width and 0.5~2 nm in thickness, revealed by high-resolution transmission electron microscopy and atomic force microscopy. In addition, Fourier transform infrared spectrum evidences the existence of carbonyl and hydroxyl groups, meaning GQDs can be dispersed in water easily and used in cellar imaging, and blue area inside L929 cells were clearly observed under the fluorescence microscope. Both low price of raw material and simple prepared method contribute to the high quality GQDs widespread application in future.

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 Graphene quantum dots based on maltose as a high yield photocatalyst for efficient photodegradation of imipramine in wastewater samples

2020 ◽  
Vol 18 (2) ◽  
pp. 1531-1540
Author(s):  
Raheleh Hatefi ◽  
Ali Mashinchian-Moradi ◽  
Habibollah Younesi ◽  
Saeed Nojavan
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
High Yield ◽  
Wastewater Samples

Towards scalable synthesis of high-quality PbS colloidal quantum dots for photovoltaic applications

2019 ◽  
Vol 7 (6) ◽  
pp. 1575-1583 ◽  
Author(s):  
Sijie Zhou ◽  
Zeke Liu ◽  
Yongjie Wang ◽  
Kunyuan Lu ◽  
Fan Yang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Large Scale ◽  
Colloidal Quantum Dots ◽  
High Yield ◽  
High Quality ◽  
Excellent Quality ◽  
Photovoltaic Applications ◽  
Photovoltaic Technology ◽  
Scalable Synthesis ◽  
Large Scale Manufacture

Accelerating inorganic nanocrystal-based photovoltaic technology needs more efficient synthetic protocols for large scale manufacture, high yield and excellent quality nanocrystal materials.

Fine Grinding of Silicon Wafers: Grinding Marks

2002 ◽  
Author(s):  
Z. J. Pei ◽  
Alan Strasbaugh
Keyword(s):  
Silicon Wafer ◽  
Low Cost ◽  
Base Material ◽  
Silicon Wafers ◽  
High Yield ◽  
Manufacturing Processes ◽  
High Quality ◽  
Fine Grinding ◽  
Etched Silicon

In order to ensure high quality chips with high yield, the base material, semiconductor wafers (over 90% are silicon), must have superior quality. It is critically important to develop new manufacturing processes that allow silicon wafer manufacturers to produce high quality wafers at a reasonably low cost. A newly patented technology—fine grinding of etched silicon wafers—has great potential to manufacture very flat silicon wafers more cost-effectively. This paper presents an investigation of grinding marks in fine grinding. The investigation covers (1) nature of grinding marks, (2) factors that have effects on grinding marks, and (3) approaches to reduce grinding marks. Varying chuck speed during grinding operation is shown to be a very effective approach to reduce grinding marks. Conclusions from this study have direct impacts to the silicon wafer industry.

A fluorometric assay for tyrosinase activity and its inhibitor screening based on graphene quantum dots

RSC Advances ◽  
2016 ◽  
Vol 6 (76) ◽  
pp. 72670-72675 ◽  
Author(s):  
X. E. Zhao ◽  
C. H. Lei ◽  
Y. H. Wang ◽  
F. Qu ◽  
S. Y. Zhu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Tyrosinase Activity ◽  
Fluorometric Assay ◽  
Pristine Graphene ◽  
Fluorescence Sensing ◽  
Inhibitor Screening ◽  
Sensing Platform ◽  
First Time

Pristine graphene quantum dots (GQDs) without any functionalization were used as probes to develop a sensitive and selective fluorescence sensing platform for the detection of tyrosinase (TYR) activity and its inhibitor screening for the first time.

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