Modified hummers method Graphene Oxide – Single & Few Layer Layers, a variety of platelet sizes, high oxygen content, & freeze dried to preserve solubility
Reduced Graphene Oxide
Graphene Oxide Gel
Graphene Oxide and Reduced Graphene Oxide are available in powder form, as a dispersion, or as a spin coated film which is available in oxide or reduced forms. Please contact us today to discuss your needs.
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Graphene Oxide synthesis methods have been known for decades. Originally called graphite oxide, it is a compound of carbon, oxygen, and hydrogen in variable ratios. It is synthesized by exfoliating graphite with strong oxidizers, rinsed repeatedly until the the rinse water is PH neutral and then freeze dried to preserve solubility. Many companies try to reduce the rinsing or skip the freeze drying but they are critical to success in using the product. The bulk product is a brownish/yellowish solid material that retains the layer structure of graphite but with a much larger and irregular spacing. It doesn’t require post production functionalization as it consists of graphene sheets with hydroxyl, carboxyl, & epoxide groups. It is soluble in Di water, NMP, DMF, THF, Ethanol, and other solvents that behave like water. GO can be reduced using several methods such as laser, microwave, electrochemically, hydrazine vapor treatment, or by annealing at temperatures from 250-400C in a forming gas (95% argon, 5% hydrogen) environment yielding the intrinsically high electrical and thermal conductivity of graphene.
Molecular Structure of Graphene Oxide
The molecular structure of graphene oxide is shown below. The functional groups are present on the edges of the flakes and on the top and bottom which helps impart graphene oxide with legendary solubility compared to most nanoscale particles. No surfactants are needed when dispersing into typical solvents such as Di Water, NMP, DMF, THF, DCB, or ethanol.
Graphene Oxide Applications
Graphene Oxide applications are numerous due to its high solubility and the ability to reduce it to near perfect graphene. This overcomes the well known dispersion problems with other nanomaterials enabling you to get the full benefits of nanoscale additives such as improved mechanical properties as well as enhanced conductivity.
Reduced Graphene Oxide
Reduced graphene oxide first undergoes the typical synthesis process and then it is reduced which removes most of the surface functional groups as well as restores the molecular structure to one much closer to pristine graphene than graphene oxide.
There are a number of ways reduction can be achieved and is typically a chemical, thermal or electrochemical process. Some of these techniques are able to produce very high quality rGO, similar to pristine graphene, but can be complex or time consuming to carry out.
Common graphene reduction techniques are:
Treating GO with hydrazine hydrate and maintaining the solution at 100c for 24 hours
Exposing GO to hydrogen plasma for a few seconds
Exposing GO to another form of strong pulse light, such as those produced by xenon flashtubes
Heating GO in distilled water at varying degrees for different lengths of time
Directly heating GO to very high levels in a furnace
Directly heating GO in a microwave
At 400C in a forming has atmosphere 95% argon, 5% hydrogen
Chemical reduction is a highly scalable method, unfortunately the reduced graphene oxide produced often has resulted in relatively poor yields in terms of surface area and electronic conductivity. Thermally reducing graphene oxide at temperatures of 1000℃ or more creates rGO that has been shown to have a very high surface area but the annealing process damages the structure of the graphene oxide when pressure between builds up and carbon dioxide is released. During reduction, there is a substantial reduction in the mass of the graphene oxide (figures around 30% have been mentioned) which creates imperfections and voids in the structure and interferes with its unique properties.
Electrochemical reduction of graphene oxide is a method that has been shown to produce very high quality reduced graphene oxide, almost identical in terms of structure to pristine graphene.
Once reduced graphene oxide has been produced, it can be selectively functionalized thus enabling its use in different applications. By treating reduced graphene oxide with other chemicals or by creating new compounds when combining reduced graphene oxide with other two dimensional materials, we can engineer the surface chemistry of the compound to the specific application.
Graphene Oxide Paper
Graphene Oxide Paper is relatively easy to make. Graphene oxide is known to disperse very easily due to the type and amount of functional groups on its surface. To make graphene oxide paper folks typically disperse the graphene oxide in a solvent such as water or an organic solvent and then using a 0.2um membrane filter, they pour the graphene oxide solution through a vacuum filtration apparatus and the membrane keeps the particles on top while the solvent is collected below. When dry, the membrane can be removed leaving a free standing graphene oxide paper product. Reduced graphene oxide paper can be made by similar methods.
Graphene oxide dispersions are available from Cheap Tubes Inc. Please let us know your reqirements such as solvent and loading ratio. Our standard concentration is 2mgs/ml but we can go up to 10mgs/ml.
Publications using Graphene Oxide from Cheap Tubes Inc
Below are some publications that used graphene oxide from Cheap Tubes Inc.