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: Chemical vapor deposition used to grow atomic layer materials on top of each other

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

Thinnest feasible nano-membrane produced

4 hours ago

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...

Wiring up carbon-based electronics

6 hours ago

Carbon-based nanostructures such as nanotubes, graphene sheets, and nanoribbons are unique building blocks showing versatile nanomechanical and nanoelectronic properties. These materials which are ordered ...

Making 'bucky-balls' in spin-out's sights

Apr 16, 2014

(Phys.org) —A new Oxford spin-out firm is targeting the difficult challenge of manufacturing fullerenes, known as 'bucky-balls' because of their spherical shape, a type of carbon nanomaterial which, like ...

User comments : 0

More news stories

Thinnest feasible nano-membrane produced

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...

Wiring up carbon-based electronics

Carbon-based nanostructures such as nanotubes, graphene sheets, and nanoribbons are unique building blocks showing versatile nanomechanical and nanoelectronic properties. These materials which are ordered ...

Hackathon team's GoogolPlex gives Siri extra powers

(Phys.org) —Four freshmen at the University of Pennsylvania have taken Apple's personal assistant Siri to behave as a graduate-level executive assistant which, when asked, is capable of adjusting the temperature ...

Deadly human pathogen Cryptococcus fully sequenced

Within each strand of DNA lies the blueprint for building an organism, along with the keys to its evolution and survival. These genetic instructions can give valuable insight into why pathogens like Cryptococcus ne ...

Researchers discover target for treating dengue fever

Two recent papers by a University of Colorado School of Medicine researcher and colleagues may help scientists develop treatments or vaccines for Dengue fever, West Nile virus, Yellow fever, Japanese encephalitis and other ...