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Graphene Presentation
It's simple to understand the synthesis. Hydrothermal method is a chemical reaction in water in a sealed pressure vessel, which is in fact a type of reaction at both high temperature and pressure.
For free download Subscribe to https://www.youtube.com/channel/UCTfiZ8qwZ_8_vTjxeCB037w and Follow https://www.instagram.com/fitrit_2405/ then please contact +91-9045839849 over WhatsApp.
Graphene Presentation
It's simple to understand the synthesis. Hydrothermal method is a chemical reaction in water in a sealed pressure vessel, which is in fact a type of reaction at both high temperature and pressure.
know more about nanomaterials and its apllication in future as well as current situation, and what wil we reserch on basis of nanomaterials and carbon structure and its aplication in such futuriastic manner.
Chemical Vapour Deposition is a Chemical Synthesis route of Nanomaterials. Specially thin films like Graphene and Carbon NanoTubes are grown by this method.
Graphene, the amazing two-dimensional carbon nanomaterial, has attracted extensive interest in recent years and emerged as the most intensively studied material [1]. In 2004, Geim and Nosovelov at Manchester University successfully isolated single layer graphene by the mechanical cleavage of graphite crystal [2]. This ‘‘thinnest’’ known material exhibits extraordinary electronic, chemical, mechanical, thermal and optical properties which bestowed graphene as a miracle material of the 21st Century. From applicative perspectives, graphene holds a great promise with the potential to be used as energy-storage materials, in nanoelectronics, in catalysis, biomedical, in polymer composites and many more.
This presentation contains various aspects of Graphene like synthesis techniques, characterization, commercialization, mechanical and electrical properties and present and future application.
know more about nanomaterials and its apllication in future as well as current situation, and what wil we reserch on basis of nanomaterials and carbon structure and its aplication in such futuriastic manner.
Chemical Vapour Deposition is a Chemical Synthesis route of Nanomaterials. Specially thin films like Graphene and Carbon NanoTubes are grown by this method.
Graphene, the amazing two-dimensional carbon nanomaterial, has attracted extensive interest in recent years and emerged as the most intensively studied material [1]. In 2004, Geim and Nosovelov at Manchester University successfully isolated single layer graphene by the mechanical cleavage of graphite crystal [2]. This ‘‘thinnest’’ known material exhibits extraordinary electronic, chemical, mechanical, thermal and optical properties which bestowed graphene as a miracle material of the 21st Century. From applicative perspectives, graphene holds a great promise with the potential to be used as energy-storage materials, in nanoelectronics, in catalysis, biomedical, in polymer composites and many more.
This presentation contains various aspects of Graphene like synthesis techniques, characterization, commercialization, mechanical and electrical properties and present and future application.
A key vacuum deposition technique for making highly homogenous and high-performance solid-state thin films and materials is Chemical vapor deposition. The types of CVD systems and their key applications would also be discussed in this presentation. It is a key bottom-up processing technique, widely used in graphene fabrication, also the fabrication of various oxides, nitrides is possible, with this technique.
Graphene: the world's first 2D material. Since graphene's isolation in 2004, it has captured the attention of scientists, researchers, and industry worldwide.
Nanocoating GDZ is compared with Conventional YSZ coating for Hot Corrosion Resistance in presence of V2O5 and Na2SO4 salt which are formed at high temp in gas turbines.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
Vaccine management system project report documentation..pdfKamal Acharya
The Division of Vaccine and Immunization is facing increasing difficulty monitoring vaccines and other commodities distribution once they have been distributed from the national stores. With the introduction of new vaccines, more challenges have been anticipated with this additions posing serious threat to the already over strained vaccine supply chain system in Kenya.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
3. Introduction
• Graphene : Carbon in 2D
• 2-dimensional, crystalline
allotrope of carbon.
• Carbon atoms are densely
packed in a regular sp2-
bonded atomic-scale
hexagonal pattern.
.
Fig1: High resolution TEM images
of graphene
http://en.wikipedia.org/wiki/Graphene
4. Properties
• Electronic properties
– High electrical conductivity
– Semi metal/zero gap semiconductor
– High electron mobility
• Mechanical properties
– One of the strongest material
– Ultimate tensile strength is 130GPa (0.4 GPa-Steel)
– Very light
– High surface area to volume ratio.
– Has elastic properties too (Young’s modulus – 0.5TPa)
5. Properties
• Optical properties
– Single layer of graphene absorbs spectrum as high as 2.3%
of white light
– Saturation absorption under strong excitation
• Wetting properties
– Super hydrophobic property
– Super hydrophilic property
6. Applications
• Electrochemical storage devices
Super-capacitors, graphene-enhanced lithium ion batteries.
• Biological Engineering
Tissue regeneration- potential biocompatibility.
• Aerospace applications
Integration into other composite materials.
• Water purification systems
Monolayer graphene- ultrafilteration.
Some of the major applications of graphene are:
7. Applications
• Opto-Electronic applications
Replacing Indium Tin Oxide.
• Photovoltaic Cells
Replacing Si Solar cells and ITO in DSSC.
• Various other applications which involve enhancing electrical, mechanical
and various other properties of devices or materials as such.
8. Methods Used
• Chemical Vapour Deposition (CVD).
• Mechanical Exfoliation.
• Epitaxial Growth of Graphene on SiC.
• Chemical Methods such as Hummers Method.
• Electrochemical Exfoliation.
Various Methods used till date are as follows:
9. CVD (Chemical Vapour Deposition)
• A way of depositing gaseous reactants on a substrate.
• The process is similar to PVD (Physical Vapour Deposition) the
only difference being the use of solid reactants instead of
gaseous reactants as in CVD.
• The carrier gases are combined in a reaction chamber which
is maintained at certain temperature and pressure (as
required by reaction).
• The reaction occurs on the substrate on which one of the
product (carbon) is deposited and the by products are
pumped out.
• Substrate is usually a transition metal (Ni/Cu) or some
ceramic such as glass.
• The selection of substrate depends upon the feasibility of
transferring the graphene onto the required material.
10. • The gases used are generally Methane (source of carbon)
Hydrogen and Argon are also used along with methane as
reaction stabilizers and enhancing the film uniformity.
• Although there are various types of CVD processes but most
modern processes (regarding CVD pressure) are as follows:
-> LPCVD (Low Pressure CVD): Carried out under sub-atmospheric
pressures. Low pressure prevents unwanted reactions and also
increase the uniformity of the films on the substrate.
-> UHVCVD (Ultra High Vacuum CVD): Carried out under extremely
low atmospheric pressures (6-10 Pa).
CVD (Chemical Vapour Deposition)
12. CVD (Chemical Vapour Deposition)
ADVANTAGES-
• High quality, impervious, and harder graphene is obtained.
• Producing large domains of graphene is easy.
• High growth rates possible.
• Good reproducibility.
LIMITATIONS-
• High temperatures (greater than 900 °C) leads to wrinkled
graphene due to difference in Coefficient of Thermal Expansion.
• Complex process.
• Production of corrosive and toxic gases.
• Difficulty in controlling the thickness in some cases (number of
layers).
• Difficulty in transferring the film to other surface (exfoliation).
• Difficulty in achieving the uniform deposition of the carbon.
13. Mechanical Exfoliation
Process:
• A fresh piece of Scotch tape is taken (about six inches long).
• The adhesive side is pressed onto the HOPG (Highly Ordered
Pyrolytic Graphite) for about ten seconds.
• The tape is gently peeled away with thick shiny layers of graphite
attached to it.
• The part of the tape with layers from the HOPG was refolded
upon a clean adhesive section of the same piece of the tape and
then the tape is unfolded.
• This process is repeated several times until the end of the tape is
no longer shiny but becomes dark/dull and grey.
• These graphite layers on the tape are transferred onto the
surface of the Si/SiO2 wafers by gently pressing them onto the
tape for some time and then peeling off.
• The wafers are then examined using various characterization
techniques.
14. Mechanical Exfoliation
(a) Adhesive tape is pressed onto the HOPG.
(b) The tape is peeled off when some layers stick to the surface.
(c) This tape is pressed onto the surface of the target substrate.
(d) The tape is peeled off when the layers stick to the target surface.
Fig3: Schematic diagram for the mechanical exfoliation of graphene from graphite using Scotch tape.
K S Novoselov and A H Castro Neto 2012 Phys. Scr. 2012 014006, Two-dimensional crystals-based heterostructures: materials with tailored
properties.
15. Mechanical Exfoliation
Advantages:
• Safe and simple process.
• Few layer graphene can be easily obtained.
• The chances of impurity in the graphene so obtained are less.
• Sample preparation is simplified.
Limitations:
• Yield obtained may not meet the requirements.
• Requires skilled manual labour.
• Despite the fact that tape residue does not seriously affect the
quality of the graphene flake samples, it does make those
samples more difficult to find on the substrate.
16. • The main concept behind the process is that the vapour pressure
of Silicon is higher, as a result on heating the SiC wafer, the Si
evaporates leaving behind the graphene layers on the SiC.
• The theoretical studies show the various stable structures of
carbon that grow on SiC which determines the mechanism for
growth of carbon layers on SiC substrate.
• The evaluation of number of graphene layers is done by
observing the quantized oscillations of the electron reflectivity.
• Multilayer, bilayer or single layer graphene can be grown on the
SiC substrate by controlling various parameters such as SiC
temperature and pressure.
• Graphene single crystals can also be synthesized using this
process since few layer graphene (FLG) always maintains it’s
epitaxial growth with the SiC substrate.
Epitaxial Growth of Graphene on SiC
17. Epitaxial Growth of Graphene on SiC
Fig4: Schematic illustration of the
thermal decomposition method.
Hiroki Hibino†, Hiroyuki Kageshima, and Masao
Nagase, “Graphene Growth on Silicon Carbide”,
NTT Technical review.
• The SiC substrate is heated at a temperature (around 1200 °C)
and the conditions of the chamber are set accordingly.
• UHV (Ultra High Vacuum) technique hinders the uniform
growth of MLG (Multi Layer Graphene) and favor the bilayer
graphene.
• The Si atoms evaporate due to thermionic emission leaving
behind the carbon atoms on the remaining substrate.
• The carbon layers accumulating on the substrate are
controlled by controlling the temperature and pressure.
• The final SiC substrate is covered with the carbon layers
which can be either bilayer, monolayer or multilayer
graphene.
• The type is distinguished by using the suitable
characterization techniques (such as TEM), the shade of the
layer in the images can be used as the classifying method for
recognizing the type of graphene.
18. Epitaxial Growth of Graphene on SiC
Advantages:
• High quality graphene.
• Easy method for growing single crystals of graphene.
• The layers of graphene can be controlled conveniently.
• Higher temperatures ensure reproducible, clean and ordered graphene.
• Patterning of graphene is easier due to the use of insulating SiC
substrate.
• Further advantage is that SiC is already a large bandgap semiconductor
already used in electronic applications.
Limitations:
• High temperature.
• Difficulty in growing uniform MLG in UHV conditions (impurity
free conditions).
• Lattice constant mismatch and difference in coefficient of
thermal expansion of SiC - C can lead to various defects.
19. • The Hummers method is used for producing graphene by oxidising graphite to
GO by using suitable oxidising agents such as KMnO4.
• The GO so produced is again then chemically reduced to get graphene.
• The modified Hummers method introduces a way to get a more stable GO
colloidal solution.
• Ultra-sonication is used for stabilizing the GO solution and enhancing the
exfoliation in the GO solution.
Hummers Method (modified)
Fig5: A typical illustration of the difference between the graphite and the GO so formed.
Mateusz CISZEWSKI, Andrzej MIANOWSKI, “Survey of graphite oxidation methods using oxidizing mixtures in inorganic acids”, CHEMIK International Edition,
CHEMIK 2013, 67, 4, 267-274
20. The modified hummers method can be carried out in three major steps as follows:
Oxidation
• Natural graphite flake is mixed with a strong acid such as H2SO4 /HNO3 followed by
continuous stirring in ice bath.
• Then KMnO4 is added and stirred at room temperature.
• Then the solution is kept overnight after adding DI water and H2O2.
• Centrifugation is used for dilution until the pH is around 7.
• Ultra-sonication is carried out to get monolayer GO.
Reduction
• Addition of certain reducing agents such as hydrazine or NaBH4 is made to the measured
solution.
• The attached functional groups are removed and to enhance the exfoliation certain polar
aprotic solvents can be used along with organic compounds.
• Although thermal reduction gives a better quality graphene but has its own disadvantages.
Post-treatment
• Then the solution is filtered and washed with DI water until neutrality.
• The product is dried and grinded.
• The graphene so produced can then be send for characterization tests.
Hummers Method (modified)
21. Hummers Method (modified)
Advantages:
• High yield.
• Scalable to industrial level.
Limitations:
• The defects on graphene sheets are inevitable.
• The process is time consuming and can be laborious.
• The thickness control is not as promising as in the epitaxial graphene
growth or the CVD process.
22. Electrochemical Exfoliation
• The electrochemical exfoliation method is an eco-friendly method fro producing high quality
graphene.
• The electrochemical exfoliation of graphite due to the ions present in the solution give the
FLG or GO depending upon the nature of electrolyte.
• The choice of electrolyte is based on the requirement of the oxidizing environment and
more importantly on the size of the intercalating ion.
• The setup includes two electrodes one of them being graphite or HOPG the other can be Cu,
Pt or can be HOPG/graphite also.
• A voltage of +/- 10V is applied generally for an unequal period of time.
• The intercalating ion in the solution exfoliates the graphite into FLG by penetrating in
between the sheets due to the applied voltage.
• The need for negative voltage is to bring the intercalated ions back into the solution along
with the sheets, hence the need of unequal application time for the voltages.
• The electrolyte used is often diluted with DI water and then at the end of the process the
solution is taken for centrifugation to separate the graphite particles from graphene/GO.
• The solution can also be subjected to ultra-sonication for enhancing the exfoliation and
some stabilizers can also be used for the solution.
• The final solution is either dried or taken directly for characterization.
23. Electrochemical Exfoliation
AC voltage/555 timer
Graphite rod Graphite rod
Electrolyte
Fig6: A basic setup for the process is illustrated in the following figure.
Fig7: Schematics of the exfoliation mechanism for the peroxide electrolyte. The mechanism may
differ depending upon the nature of ions/electrolyte.
K.S.Rao , J.Senthilnathan, Y.F.Lui, M.Yoshimura, Role of peroxide ions in formation of graphene nanosheets by electrochemical exfoliation of graphite, Scientific
reports 4, Article number:4237, 2014
24. Electrochemical Exfoliation
Advantages:
• High yield.
• Scalable to industrial level.
• Easy to operate and relatively a faster approach.
• Eco-friendly.
• FLG can be easily obtained.
• The graphene obtained can be functionalised depending upon
electrolyte and hence can be more compatible with certain organic
compounds or polymers.
Limitations:
• The impurities may be present in the form of unwashed salts in
between the graphene layers.
• This may affect the conductivity of the graphene.
• The thickness control is not as promising as in the epitaxial graphene
growth or the CVD process.
25. N-doped Graphene
• The electronic properties of graphene doped with
nitrogen or boron are enhanced similar to the case of
doped Si.
• The doping depends upon the type of graphene used,
hence depends upon the initial process used for the
synthesizing the graphene.
• Till now various methods are used for synthesizing N-
doped graphene, some of them are as follows:
1) Co-growth of ammonia and methane by CVD.
2) Arc discharge of graphite.
3) Annealing of GO with ammonia.
4) Treating graphene with nitrogen plasma.
Manipulation of these properties via chemical functionalization / surface modification makes it rapid growing field in material science.
Graphene can be saturated readily under strong excitation over the visible to near-infrared region, due to the universal optical absorption and zero band gaps. This has relevance for the mode locking of fiber lasers, where full band mode locking has been achieved by graphene-based saturable absorber. Due to this special property, graphene has wide application in ultrafast photonics. Moreover, the optical response of graphene/graphene oxide layers can be tuned electrically.
n epitaxial method in which graphene results from
the high temperature reduction of silicon carbide
38
-
40
118
-
120
The process is relatively straightforward, as
silicon desorbs around 1000°
C in ultrahigh vacuum. This
leaves behind small islands of graphitized carbon
The furnace (reaction chamber) is quickly cooled to keep the deposited carbon layer from
aggregating into bulk graphite, which crystallizes into a contiguous graphene
layer on the surface of the metal.