New findings on the structure of graphite oxides in alcohols

Feb 06, 2013 by Ingrid Söderbergh

(Phys.org)—The structure of graphite oxide surprisingly expands when cooled in methanol or ethanol. Also, graphite oxide selectively absorbs methanol from water-methanol mixtures. Two new studies by physicists at Umeå University in Sweden, published in ACS Nano and J. Phys. Chem. C, respectively, provide knowledge on new properties of oxidized graphite and graphene.

Graphene is a two dimensional material consisting of a single layer of arranged in a . Graphene can be considered as a unique adsorbent material due to its extremely . One gram of graphene has a surface area comparable to a football field. This surface could be used for adsorption of gases and liquids, in applications for , extraction of pollutants from water, etc. However, the graphene is hydrophobic, which means that its surface repels water.

On the other hand, oxidation of graphene results in remarkable changes in its properties. Graphene oxide is hydrophilic and it is also easily soluble in water. A material composed of many stacked graphene oxide layers is called graphite oxide. It has many : it absorbs water and alcohols in large amounts, similar to clays that swell when water is added.

A new study by Alexandr V. Talyzin and his team reveals that graphite oxide is able to incorporate even more and ethanol at low temperatures compared to room temperature. Its structure expands when cooled in an excess of liquid solvent. At -130 degrees Celsius the graphene oxide layers are separated by 20.4 Å due to incorporation of additional ethanol into its structure, compared to approximately 3.4 Å in natural graphite and approximately 6.5 Å in solvent-free graphite oxide.

"The distance between graphene oxide layers at low temperatures is so large that it becomes a with graphene oxide sheets separated by at least four of methanol or molecules. What is also remarkable is that this phenomenon is limited only to one specific type of graphite oxide and is not observed in another type studied. In fact, many different kinds of graphite oxide are known and now we start to understand how enormous the variations of their properties are. It is not just one material, it is a whole family of materials," says Alexandr V. Talyzin, researcher at the Department of Physics.

In a separate study published in J. Phys. Chem. C it was demonstrated that a certain type of graphite oxide can be used for selective absorption of methanol from water-methanol mixtures. A very simple prototype filtering experiment showed that when a water-methanol liquid mixture is passed through graphite oxide powder, some of the methanol is absorbed in the powder and the solution passing through contains more pure water.

"In the future we would like to design special membranes composed of graphene oxide layers, which can be used for separation of different solvents and purification of water. These first results help us to understand possible ways to make such membranes," says Alexandr V. Talyzin.

The first example of successful solvent separation effects was reported last year in a study by R.R. Nair et al. from a research team at Manchester University, lead by I.Grigorieva and Nobel Laureate A. Geim, famous for their research in the graphene field.

Explore further: The latest fashion: Graphene edges can be tailor-made

More information: You, S. et al. Enormous Lattice Expansion of Hummers Graphite Oxide in Alcohols at Low Temperatures. ACS Nano, Article ASAP. DOI: 10.1021/nn3051105

You, S. et al. Selective Intercalation of Graphite Oxide by Methanol in Water/Methanol Mixtures. J. Phys. Chem. C, Article ASAP. DOI: 10.1021/jp312756w

Related Stories

Graphite + water = the future of energy storage

Jul 15, 2011

A combination of two ordinary materials – graphite and water – could produce energy storage systems that perform on par with lithium ion batteries, but recharge in a matter of seconds and have an ...

Recommended for you

The latest fashion: Graphene edges can be tailor-made

Jan 23, 2015

Theoretical physicists at Rice University are living on the edge as they study the astounding properties of graphene. In a new study, they figure out how researchers can fracture graphene nanoribbons to get ...

Nanotechnology changes behavior of materials

Jan 23, 2015

One of the reasons solar cells are not used more widely is cost—the materials used to make them most efficient are expensive. Engineers are exploring ways to print solar cells from inks, but the devices ...

Gold 'nano-drills'

Jan 22, 2015

Spherical gold particles are able to 'drill' a nano-diameter tunnel in ceramic material when heated. This is an easy and attractive way to equip chips with nanopores for DNA analysis, for example. Nanotechnologists ...

The importance of building small things

Jan 22, 2015

Strong materials, such as concrete, are usually heavy, and lightweight materials, such as rubber (for latex gloves) and paper, are usually weak and susceptible to tearing and damage. Julia R. Greer, professor ...

Graphene brings quantum effects to electronic circuits

Jan 22, 2015

Research by scientists attached to the EC's Graphene Flagship has revealed a superfluid phase in ultra-low temperature 2D materials, creating the potential for electronic devices which dissipate very little ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.