scholarly journals Preparation of Colloidal Dispersions of Graphene Sheets in Organic Solvents by Using Ball Milling

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Weifeng Zhao ◽  
Furong Wu ◽  
Hang Wu ◽  
Guohua Chen
Keyword(s):  
Organic Solvents ◽  
Colloidal Suspension ◽  
Colloidal Dispersions ◽  
Graphene Sheets ◽  
Graphite Nanosheets ◽  
Force Microscopy ◽  
Layer Graphene ◽  
Atomic Force ◽  
Transmission Electron ◽  
Few Layer Graphene

A top-down method was developed for producing colloidal dispersions of graphene sheets. Graphite nanosheets comprising hundreds of carbon layers were dispersed and gently ball-milled to exfoliate into graphene in a variety of organic solvents. After 30 hours of the shear-force-dominated grinding and a subsequent 4000 r.p.m. of centrifugation, single- and few-layer graphene sheets were readily prepared and homogeneously and stably suspended in the good solvent medium which possesses a surface tension value close to 40 mJm−2, such as inN,N-dimethylformamide, at a concentration up to 0.08 mg ml−1, achieving a yield higher than 32.0 wt%. The graphene materials in the colloidal suspension were characterized using scanning and transmission electron microscopy and atomic force microscopy.

scholarly journals Growth of Ordered Graphene Ribbons by Sublimation Epitaxy

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 449
Author(s):  
Shuxian Cai ◽  
Xingfang Liu ◽  
Xin Zheng ◽  
Zhonghua Liu
Keyword(s):  
Substrate Surface ◽  
Graphene Film ◽  
Graphene Ribbon ◽  
High Quality ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Layer Graphene ◽  
Micro Raman Spectroscopy ◽  
Atomic Force ◽  
Few Layer Graphene

Ordered graphene ribbons were grown on the surface of 4° off-axis 4H-SiC wafers by sublimation epitaxy, and characterized by using scanning electron microscopy (SEM), atomic force microscopy (AFM) and micro-Raman spectroscopy (μ-Raman). SEM showed that there were gray and dark ribbons on the substrate surface, and AFM further revealed that these ordered graphene ribbons had clear stepped morphologies due to surface step-bunching. It was shown by μ-Raman that the numbers of graphene layers of these two types of regions were different. The gray region was composed of mono- or bilayer ordered graphene ribbon, while the dark region was of tri- or few-layer ribbon. Meanwhile, ribbons were all homogeneous and had a width up to 40 μm and a length up to 1000 μm, without micro defects such as grain boundaries, ridges, or mono- and few-layer graphene mixtures. The results of this study are useful for optimized growth of high-quality graphene film on silicon carbide crystal.

Tunable Organogelator from Alkyl-Polypeptide Diblock Prepared by Ring-Opening Polymerization

2014 ◽  
Vol 67 (1) ◽  
pp. 59 ◽  
Author(s):  
Chongyi Chen ◽  
Decheng Wu ◽  
Wenxin Fu ◽  
Zhibo Li
Keyword(s):  
Atomic Force Microscopy ◽  
Organic Solvents ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Low Concentration ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Circular Dichroïsm ◽  
Β Sheet

Three alkyl-polypeptide hybrid amphiphiles were synthesized by the ring-opening polymerization (ROP) of γ-(2-methoxyethoxy)esteryl-l-glutamate N-carboxyanhydride (l-EG1Glu NCA) using alkylamine, i.e. C6H13NH2, C14H29NH2, and C16H33NH2, as initiators. As-prepared alkyl-poly-l-EG1Glu hybrids were found to form clear organogels in several organic solvents at low concentration. FTIR and circular dichroism characterizations suggested that poly-l-EG1Glu formed a predominantly β-sheet conformation, which accounted for the gelation. Transmission electron and atomic force microscopy characterizations revealed that these copolymers formed nanoribbon structures in THF.

Solid Phase Growth of Graphene on Silicon Carbide by Nickel Silicidation: Graphene Formation Mechanisms

2014 ◽  
Vol 778-780 ◽  
pp. 1162-1165
Author(s):  
Enrique Escobedo-Cousin ◽  
Konstantin Vassilevski ◽  
Toby Hopf ◽  
Nicholas Wright ◽  
Anthony G. O'Neill ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Solid Phase ◽  
Formation Mechanisms ◽  
Layer By Layer ◽  
Phase Growth ◽  
Force Microscopy ◽  
Layer Graphene ◽  
Atomic Force ◽  
High Temperature Stage ◽  
Few Layer Graphene

This work presents experimental evidence of the formation mechanisms of few-layer graphene (FLG) films on SiC by nickel silicidation. FLG is formed by annealing of a 40 nm thick Ni layer on 6H-SiC at 1035ºC for 60 s, resulting in a Ni2Si layer which may be capped by any Ni that did not react during annealing. It has been proposed that FLG forms on top of the Ni during the high temperature stage. In contrast, during cooling, carbon atoms which were released during the silicidation reaction may diffuse back towards the Ni2Si/SiC interface to form a second FLG film. After annealing, layer-by-layer de-processing was carried out in order to unequivocally identify the FLG at each location using Atomic force microscopy (AFM) and Raman spectroscopy.

IMPROVED CHEMICAL SYNTHESIS OF GRAPHENE USING A SAFER SOLVOTHERMAL ROUTE

2011 ◽  
Vol 10 (01n02) ◽  
pp. 39-42 ◽  
Author(s):  
DILIP KUMAR SINGH ◽  
P. K. IYER ◽  
P. K. GIRI
Keyword(s):  
Electron Microscopy ◽  
Graphene Sheets ◽  
Pyrolysis Process ◽  
High Quality ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Afm Analysis ◽  
Bulk Production

Graphene has been synthesized using thermal decomposition of ethyl alcohol in a medium pressure autoclave. The synthesis was carried out in the presence of strong alkaline solution at a temperature of ~230°C and pressure of 60 bar. The as-synthesized graphene has been characterized using atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM). AFM analysis on various graphene sheets shows the presence of monolayer (n = 1) to trilayer (n = 3) graphene sheets with thickness of ~1.168 nm. HRTEM studies confirm the high quality of graphene obtained after purification of as-synthesized product. Use of chemically nonexplosive material for synthesis and reduced reaction time along with the absence of post-pyrolysis process make it a commercially viable process for bulk production of graphene.

Synthesis of Few-Layer Graphene on Copper Using a Low-Cost Atmospheric Thermal Chemical Vapour Deposition System with Methane and Forming Gas

Nano Hybrids ◽  
2016 ◽  
Vol 10 ◽  
pp. 1-13
Author(s):  
M.S. Shamsudin ◽  
S.J. Fishlock ◽  
M. Rusop ◽  
S.M. Sanip ◽  
Suan Hui Pu
Keyword(s):  
Chemical Vapour Deposition ◽  
Vapour Deposition ◽  
Low Cost ◽  
Graphene Film ◽  
Chemical Vapour ◽  
Force Microscopy ◽  
Layer Graphene ◽  
Atomic Force ◽  
Temperature Deposition ◽  
Few Layer Graphene

Graphene has attracted wide interest across a range of applications due to its electrical, mechanical and optical properties. The use of a low-cost, table-top chemical vapour deposition system to deposit few-layer graphene onto copper is reported in this work. Characterisation of the graphene is performed using Raman spectroscopy and atomic force microscopy. The results show that few-layer graphene can be deposited at 1000 °C using CH4 as a carbon precursor, and 5% H2, 95% N2 forming gas as a diluent. The effects of deposition temperature, deposition time, and forming gas addition on graphene film quality was studied experimentally. An increase in graphene quality was observed when forming gas was added during deposition.

scholarly journals Graphite Nanosheet Exfoliation From Graphite Flakes Through Functionalization Using Phthalic Acid

2015 ◽  
Vol 60 (2) ◽  
pp. 1251-1255
Author(s):  
J.H. Kim ◽  
J.-H. Lee
Keyword(s):  
Phthalic Acid ◽  
Nitrogen Atmosphere ◽  
Graphite Nanosheets ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Graphite Nanosheet ◽  
Different Temperatures ◽  
Ft Ir ◽  
Ir Analysis

AbstractIn order to fabricate graphite nanosheets from graphite flakes, edge-functionalized graphite nanosheets were prepared by a functionalization method using phthalic acid as the molecule to be grafted. A polyphosphoric acid/P2O5solution containing graphite and phthalic acid were heated at different temperatures for 72 h in a nitrogen atmosphere. It was confirmed by transmission electron microscopy and atomic force microscopy that the resultant phthalic acid-functionalized graphite nanosheets had a large surface area of 20.69μm2in average and an average thickness of 1.39 nm. It was also found by X-ray diffractometry and Fourier transform infrared spectroscopy (FT-IR) analysis that the functionalization caused the formation of C=O bonds at the edges of the graphite nanosheets. The yield from this functionalization method was found to be dependent on the reaction temperature, only when it is between 70 and 130°C, because of the dehydration of phthalic acid at higher temperatures. This was confirmed by FT-IR analysis and the observation of low thermal energies at low temperatures.

Scanning tunneling microscopy and atomic force microscopy: New tools for biology

1989 ◽  
Vol 47 ◽  
pp. 778-779
Author(s):  
CE Bracker ◽  
P. K. Hansma
Keyword(s):  
Physical Property ◽  
Scanning Probe ◽  
Scanning Tunneling ◽  
Small Scale ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
New Family ◽  
Small Probe ◽  
Atomic Force ◽  
Transmission Electron

A new family of scanning probe microscopes has emerged that is opening new horizons for investigating the fine structure of matter. The earliest and best known of these instruments is the scanning tunneling microscope (STM). First published in 1982, the STM earned the 1986 Nobel Prize in Physics for two of its inventors, G. Binnig and H. Rohrer. They shared the prize with E. Ruska for his work that had led to the development of the transmission electron microscope half a century earlier. It seems appropriate that the award embodied this particular blend of the old and the new because it demonstrated to the world a long overdue respect for the enormous contributions electron microscopy has made to the understanding of matter, and at the same time it signalled the dawn of a new age in microscopy. What we are seeing is a revolution in microscopy and a redefinition of the concept of a microscope.Several kinds of scanning probe microscopes now exist, and the number is increasing. What they share in common is a small probe that is scanned over the surface of a specimen and measures a physical property on a very small scale, at or near the surface. Scanning probes can measure temperature, magnetic fields, tunneling currents, voltage, force, and ion currents, among others.

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