Reduced Graphene Oxide
Reduced Graphene Oxide
- Carbon (C) – 91%
- Oxygen (O) – < 8%
- Sulfur (S) – < 1%
- Hydrogen (H) – 2%
- Nitrogen (N) – 0.4%
- Colour – Dark Black
- Chemical Formula – CxOyHz
- Thickness – 0.8nm – 2nm
- Purity – >99%
- Number of layers – 3-6 layers
- Later dimension – 10 microns
- BET Surface area – > 150 sq. meter/gm
- Bulk Density – 0.121 g/cc
- Electrical Conductivity – 560 S/M
The Reduced Graphene Oxide (rGO) is the result of accurate processing of the innovative material known as graphene. It enables to get the best quality graphene sheets. The carbon to oxygen ration (C/O) of rGO is higher as compared to the graphene-oxide, where it contains a least oxidized carbon atoms. It is highly conductive to the electricity and heat. We produce rGo in a powder, flakes, and film form. We also functionalized it as per the necessary application. The rGO has high aspect ration, porosity, and electro-sorption capacity.
Specification and Description of Reduced Graphene Oxide
How we manufacture rGO ?
The Reduced Graphene Oxide ( rGO ) is the result of combining carbon, hydrogen and oxygen molecules using an extensive chemical process. The process involves treating graphite with strong oxidizers (sulfuric acid). The oxidizer reacts with graphite and removes an electron during the chemical reaction. An aforementioned chemical reaction, known as ‘REDOX’ (Reduction + Oxidization). It is designed to reduce the oxidizing agent while oxidizing the reactant.
Turning graphite into rGO is a complicated process. The smaller-sized graphene-platelets form due to the oxidation of graphite. These platelets contain tiny single-layered flakes and few multi-layered graphene pieces. Converting graphene-oxide further into rGO for research or commercial use is a time-consuming and vital process.
There are several types of thermal, electrical or chemical methods that help to produce commercial rGO. Out of these, electrical reduction of graphene-oxide is known to produce incredibly high-quality rGO. It majorly finds applications in research and development (R&D) and various commercial industries as well.
There are many organizations in the world are trying to develop a method for graphene-oxide reduction. Generally, there are mainly three methods of reduction such as Chemical, Thermal, and Electrochemical reactions. There are various reducing agents as per necessity.
Reduction of Graphene Oxide
Reducing graphene oxide is essential to get high-quality Reduced Graphene Oxide. The reduction of graphene oxide converts it to its original graphene form. It removes the oxygen functional groups from the GO structure. Several methods are used to reduce graphene oxide, such as high-temperature treatment, chemical reduction, and optical or microwave-assisted reduction.
Thermal Reduction:
Graphene Oxide is treated at temperatures above 200°C with inert gases such as argon or hydrogen. This process effectively removes the functional oxide group, which reduces graphene oxide and restores some of its original properties.
This high-temperature treatment is called annealing. It improves the electrical conductivity and mechanical strength of Reduced Graphene Oxide.
Chemical Reduction:
Chemical reduction is the most common method. Chemical-reducing agents like Hydrazine, Sodium Borohydride, or Hydroquinone react with the oxygen functional groups in graphene oxide.
GO is treated with hydrazine hydrate, and the solution is maintained at 100°C for 24 hours. GO is exposed to hydrogen plasma for a few seconds in another process. These chemical reactions remove oxygen and restore the original graphene structure. These chemicals can be toxic; hence, it should be handled carefully.
Electrochemical Reduction:
In Electrochemical reduction, an electric potential is applied to a graphene oxide film or immersed in a suitable electrolyte. Electrochemical reduction is very detailed and accurate. Researchers and engineers can customize the properties of the resulting rGO according to its specific requirements.
Electrochemical reduction is commonly used for producing Reduced Graphene Oxide films or coatings. It is used where exact control over the rGO properties is required. This method produces high-quality rGO with improved electrical conductivity and other desirable characteristics.
Optical Reduction Method:
Visible light, or ultraviolet light, is used for the reduction process. Graphene oxide undergoes photochemical reactions when exposed to these lights, turning them into reduced graphene oxide. This method offers control by adjusting the light’s strength, time, and type. It is eco-friendly, as it can be done at room temperature. It does not use any harmful chemicals.
Microwave-Assisted Reduction Method:
Microwaves generate heat quickly, reducing graphene oxide uniformly and much faster than traditional methods. It is cost-effective, energy-efficient, and can be scaled up for large-scale production of rGO. However, careful optimization of microwave power and reaction conditions is essential for consistent and high-quality rGO products.
Other Methods
- Graphene oxide can also be reduced by exposing GO to intense pulse light emitted by xenon flash tubes.
- It can also be heated in distilled water at varying temperatures for different lengths of time to get reduced Graphene oxide.
Synthesis of GO Using the Tour Method
Different methods are used to prepare graphene oxide (GO). Usually, an oxidizing agent is used in an acidic environment. Electrochemical and microbial processes are also used. In 2010, Tour’s method (TO-GO) was developed by Dr. James M. Tour and his team. Here’s a simplified explanation of the Tour method for synthesizing GO:
Starting Material:
Graphite is used as the starting material.
Interlayer Compound Formation:
The graphite is mixed with a potent oxidizing agent, like a concentrated Nitric Acid (HNO3) and Sulfuric Acid (H2SO4) solution. This process forms an interlayer compound, which expands the spacing between the graphene layers.
Exfoliation:
The interlayer compound undergoes ultrasonication. High-frequency sound waves are used to disperse the graphite layers. This process exfoliates the graphite and separates individual layers of graphene oxide.
Functionalization:
During ultrasonication, the oxygen-containing functional groups (e.g., hydroxyl, epoxy, and carboxyl groups) are introduced onto the surfaces of the graphene layers, which gives graphene oxide.
Purification:
The obtained graphene oxide is washed and purified multiple times to remove any remaining acidic residues and impurities.
The Tour method is a simple and effective way to make graphene oxide. However, we must be careful because the chemicals used can be dangerous. Using different techniques, we can reduce the graphene oxide to get rGO.
Characterization Methods
Characterization methods are techniques used to analyze and evaluate the properties of Reduced Graphene Oxide after the reduction process. Researchers and engineers can understand the structural, chemical, and physical changes during the reduction process. It can also assess the quality and performance of the final rGO product.
Some characterization methods used in the reduction of GO:
Raman Spectroscopy:
It uses laser light to analyze the vibrational modes of carbon atoms in rGO. It provides information about the degree of reduction and the presence of different functional groups in rGO.
X-ray Diffraction (XRD):
XRD is used to study the crystal structure of rGO. It can reveal the changes in the graphene layers’ arrangement and provide insights into the degree of reduction.
Fourier Transform Infrared Spectroscopy (FTIR):
FTIR is commonly used to identify functional groups in reduced graphene oxide (rGO) and evaluate the degree of reduction.
Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM):
This technique is used to observe the morphology and structure of rGO at the micro and nanoscale. It provides information about the size, shape, and distribution of rGO sheets.
X-ray Photoelectron Spectroscopy (XPS):
XPS is a surface-sensitive technique used to analyze the chemical composition of rGO. It can determine the oxidation state of carbon and identify the presence of different elements on the surface.
Electrical and Mechanical Testing:
Techniques like four-point probe measurements are used to evaluate the electrical and mechanical properties of rGO. The characterization methods help to understand reduced graphene oxide’s quality, structure, and properties. These characterizations, in turn, help to optimize its performance in various applications.
Applications of Reduced Graphene Oxide
- Educational institutes, research, and industrial sectors
- Energy storage in lithium batteries
- Biomedical, Chemical sensors, and biosensors
- Graphene Research
- Batteries and supercapacitors
- LEDs and Optoelectronics
- Replacement of TCO in touch screens
- Solar Energy
- Electrochromic Devices
- Photovoltaic cells
- Membranes
- Sensors
Chemical & Thermal Properties
rGO has a variety of properties that make it a truly innovative and useful material in today’s high-tech age.
Electrical conductivity – The material is composed of single-layer carbon atoms, forming an electron pool. Here, only one electron shares a weak bond while the other 3 are firmly connected with their counterpart in the other molecule. These form a lattice structure similar to a honeycomb and make for efficient electrical conductors. These are even better than silicon and copper.
Heat conductivity – The material can withstand at extremely high temperatures. It is perfect to use in numerous applications, where highly heat-resistant and excellent materials are required.
Optical transparency – The material is highly transparent. It absorbs the significantly low amount of light. rGO dispersion rate for light is exceptionally high, making it a better choice than conventional glass in numerous applications.
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Why Techinstro?
Techinstro produces rGO by Unique modified HUMMER’S method and supplies high quality and cost-effective product around the globe. The client may buy it in retail as well as bulk quantity. For mass requirement, we offer a special price, where the client can directly contact us for purchase. We pack and supply the rGO in the best quality sterile bottles.
