Nanotechnology Now





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Interlayer distance in graphite oxide gradually changes when water is added

Scanning force microscopy images, which show the relief of a graphene oxide flake. Bright areas are "hills" and dark areas are "valleys".  The left image was recorded at low relative humidity, one can say on a dry surface. The right image was recorded at high relative humidity, 65 percent.  One can see that new bright spots appear in some regions, which are due to the insertion of water.  The overall relief becomes less flat and more curved with more hills while valleys are preserved.
Scanning force microscopy images, which show the relief of a graphene oxide flake. Bright areas are "hills" and dark areas are "valleys". The left image was recorded at low relative humidity, one can say on a dry surface. The right image was recorded at high relative humidity, 65 percent. One can see that new bright spots appear in some regions, which are due to the insertion of water. The overall relief becomes less flat and more curved with more hills while valleys are preserved.

Abstract:
Physicists from Umeň University and Humboldt University in Berlin have solved a mystery that has puzzled scientists for half a century. They show with the help of powerful microscopes that the distance between graphite oxide layers gradually increases when water molecules are added. That is because the surface of graphite oxide is not flat, but varies in thickness with "hills" and "valleys" of nanosize. The new findings are published in the scientific journal Nano Letters.

Interlayer distance in graphite oxide gradually changes when water is added

Umea, Sweden | Posted on June 30th, 2014

"Now we can better understand the mechanisms of solvent insertion between layers of graphene oxide. It increases our knowledge of the ultrathin membranes and helps to design new types of membranes with permeation properties that can be finely adjusted by adding water and various other solvents,"says Alexandr Talyzin, researcher at the Department of Physics at Umeň University.

Graphite oxide is a unique and useful material, with many unusual properties. It can easily dissolve in water and form single atomic layers of graphene oxide sheets. The super thin flakes can then be arranged in a multilayer membrane with the unique ability to incorporate various solvents between the layers.

Already in the 60's such membranes were tested for seawater desalination and filtration applications. Recent studies show that the graphene oxide membranes may also be used to separate liquids and gases. Thin graphene oxide films can separate binary gas mixtures with fairly high efficiency. Even more interesting, the separation characteristics can be finely adjusted by water vapors.

Water molecules easily penetrate between the graphene oxide layers and it has long been known that the distance between the graphene oxide layers depends on the humidity. By simple logic, it means that the distance between the layers is to change in steps corresponding to the size of the water molecules. What has puzzled scientists for half a century is that the distance between the layers, as measured by diffraction methods, is gradually changing proportionally to the humidity change.

"Obviously, we cannot put in quarter molecules or half molecules. So why do we see continuous changes in the distance between the graphene oxide layers? We decided to study the layers of graphene oxide with modern microscopic methods, which strangely enough had not been done before", says Alexandr Talyzin.

So far the puzzle had been explained with a phenomenon called interstratification - a random stacking of layers with different number of water layers - and what is measured by diffraction data has been an average value related to the different proportions between the number of layers having different degrees of hydration.

The new study conducted by physicists from Humboldt University in Berlin together with Alexandr Talyzin┤s research team at Umeň University provides a different explanation. With microscopy of very high resolution, Scanning Force Microscopy, the researchers could measure the absolute distance between two graphene oxide layer and record changes as a function of humidity.

"The distance between two single graphene oxide layers obviously changed gradually again, but the explanation for this effect was revealed as nanometer-sized areas that were not equally filled with water. Of course, the effect of interstratification was excluded in our experiments because we only studied two layers and a single distance", says Alexandr Talyzin.

The results indicate that picturing graphene oxide as a flat plane is not correct. It is, rather, a relatively thick layer (about two times the thickness of graphene) with a variation of thickness, including "hills" and "valleys" of different size. Adding water molecules increases the thickness of this layer locally, but not necessary by the exact size of the water molecule if some "valleys" are filled first. When all available water adsorption sites ("valleys") are filled, an additional water layer is added at once. This happens at very high humidity or in liquid water.

About graphite oxide:

Graphene is a thin film of carbon, only one atom thick. It is a unique adsorptive material because of its extremely large surface. One gram graphene has a surface comparable to a football field. This space would be ideal for adsorption of gases and liquids in applications for gas storage, extraction of impurities from water, and so on, unless the graphene would be hydrophobic, meaning that its surface repels water. Oxidation of graphene results in notable changes of its properties. Graphene oxide is hydrophilic and attracted to water, and is even highly soluble in water. A material consisting of many graphene oxide layers is called graphite oxide. One possible application in the environmental area is purifying contaminated soil and seawater. Graphene oxide functions as a filter that separates all other components in water, except the water molecules.

####

For more information, please click here

Contacts:
Alexandr Talyzin

46-907-866-320

Copyright © Umea University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Original article:

Related News Press

Physics

Squeezed quantum cats May 28th, 2015

Advance in quantum error correction: Protocol corrects virtually all errors in quantum memory, but requires little measure of quantum states May 27th, 2015

Researchers find the 'key' to quantum network solution May 25th, 2015

This Slinky lookalike 'hyperlens' helps us see tiny objects: The photonics advancement could improve early cancer detection, nanoelectronics manufacturing and scientists' ability to observe single molecules May 23rd, 2015

News and information

Squeezed quantum cats May 28th, 2015

New chip makes testing for antibiotic-resistant bacteria faster, easier: Researchers at the University of Toronto design diagnostic chip to reduce testing time from days to one hour, allowing doctors to pick the right antibiotic the first time May 28th, 2015

Collaboration could lead to biodegradable computer chips May 28th, 2015

Graphene

Dr.Theivasanthi Slashes the Price of Graphene Heavily: World first & lowest price ľ Nano-price (30 USD / kg) of graphene by nanotechnologist May 26th, 2015

Haydale Named Lead Sponsor for Cambridge Graphene Festival May 22nd, 2015

Discoveries

Squeezed quantum cats May 28th, 2015

New chip makes testing for antibiotic-resistant bacteria faster, easier: Researchers at the University of Toronto design diagnostic chip to reduce testing time from days to one hour, allowing doctors to pick the right antibiotic the first time May 28th, 2015

Collaboration could lead to biodegradable computer chips May 28th, 2015

Who needs water to assemble DNA? Non-aqueous solvent supports DNA nanotechnology May 27th, 2015

Announcements

Squeezed quantum cats May 28th, 2015

New chip makes testing for antibiotic-resistant bacteria faster, easier: Researchers at the University of Toronto design diagnostic chip to reduce testing time from days to one hour, allowing doctors to pick the right antibiotic the first time May 28th, 2015

Collaboration could lead to biodegradable computer chips May 28th, 2015

Controlled Release of Anticorrosive Materials in Spot by Nanocarriers May 27th, 2015

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Squeezed quantum cats May 28th, 2015

New chip makes testing for antibiotic-resistant bacteria faster, easier: Researchers at the University of Toronto design diagnostic chip to reduce testing time from days to one hour, allowing doctors to pick the right antibiotic the first time May 28th, 2015

Who needs water to assemble DNA? Non-aqueous solvent supports DNA nanotechnology May 27th, 2015

Controlled Release of Anticorrosive Materials in Spot by Nanocarriers May 27th, 2015

Water

Nanosorbent Produced in Iran to Adsorb Tiny Amounts of Aromatic Hydrocarbon from Seawater May 18th, 2015

Iran Unveils New Home-Made Medicines, Nanotechnology Products May 14th, 2015

Plugging up leaky graphene: New technique may enable faster, more durable water filters May 7th, 2015

Production of Industrial Nano-Membrane for Water, Wastewater Purification Device in Iran May 2nd, 2015

Research partnerships

Collaboration could lead to biodegradable computer chips May 28th, 2015

Supercomputer unlocks secrets of plant cells to pave the way for more resilient crops: IBM partners with University of Melbourne and UQ May 21st, 2015

Taking control of light emission: Researchers find a way of tuning light waves by pairing 2 exotic 2-D materials May 20th, 2015

Organic nanoparticles, more lethal to tumors: Carbon-based nanoparticles could be used to sensitize cancerous tumors to proton radiotherapy and induce more focused destruction of cancer cells, a new study shows May 18th, 2015

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project