Graphene Supermaterial Goes Superpermeable: Can Be Used to Distill Alcohol

Dr Nair with the membrane. (Credit: Image courtesy of Manchester University)

Wonder material graphene has revealed another of its extraordinary properties -- University of Manchester researchers have found that it is superpermeable with respect to water.

Graphene is one of the wonders of the science world, with the potential to create foldaway mobile phones, wallpaper-thin lighting panels and the next generation of aircraft. The new finding at the University of Manchester gives graphene's potential a most surprising dimension -- graphene can also be used for distilling alcohol.

In a report published in Science, a team led by Professor Sir Andre Geim shows that graphene-based membranes are impermeable to all gases and liquids (vacuum-tight). However, water evaporates through them as quickly as if the membranes were not there at all.

This newly-found property can now be added to the already long list of superlatives describing graphene. It is the thinnest known material in the universe and the strongest ever measured. It conducts electricity and heat better than any other material. It is the stiffest one too and, at the same time, it is the most ductile. Demonstrating its remarkable properties won University of Manchester academics the Nobel Prize in Physics in 2010.

Now the University of Manchester scientists have studied membranes from a chemical derivative of graphene called graphene oxide. Graphene oxide is the same graphene sheet but it is randomly covered with other molecules such as hydroxyl groups OH-. Graphene oxide sheets stack on top of each other and form a laminate.

The researchers prepared such laminates that were hundreds times thinner than a human hair but remained strong, flexible and were easy to handle.

When a metal container was sealed with such a film, even the most sensitive equipment was unable to detect air or any other gas, including helium, to leak through.

It came as a complete surprise that, when the researchers tried the same with ordinary water, they found that it evaporates without noticing the graphene seal. Water molecules diffused through the graphene-oxide membranes with such a great speed that the evaporation rate was the same independently whether the container was sealed or completely open.

Dr Rahul Nair, who was leading the experimental work, offers the following explanation: "Graphene oxide sheets arrange in such a way that between them there is room for exactly one layer of water molecules. They arrange themselves in one molecule thick sheets of ice which slide along the graphene surface with practically no friction.

"If another atom or molecule tries the same trick, it finds that graphene capillaries either shrink in low humidity or get clogged with water molecules."

"Helium gas is hard to stop. It slowly leaks even through a millimetre -thick window glass but our ultra-thin films completely block it. At the same time, water evaporates through them unimpeded. Materials cannot behave any stranger," comments Professor Geim. "You cannot help wondering what else graphene has in store for us."

"This unique property can be used in situations where one needs to remove water from a mixture or a container, while keeping in all the other ingredients," says Dr Irina Grigorieva who also participated in the research.

"Just for a laugh, we sealed a bottle of vodka with our membranes and found that the distilled solution became stronger and stronger with time. Neither of us drinks vodka but it was great fun to do the experiment," adds Dr Nair.

The Manchester researchers report this experiment in theirScience paper, too, but they say they do not envisage use of graphene in distilleries, nor offer any immediate ideas for applications.

However, Professor Geim adds 'The properties are so unusual that it is hard to imagine that they cannot find some use in the design of filtration, separation or barrier membranes and for selective removal of water'.

Story Source:

The above story is reprinted from materials provided byManchester University, via AlphaGalileo.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. R. R. Nair, H. A. Wu, P. N. Jayaram, I. V. Grigorieva, A. K. Geim. Unimpeded Permeation of Water Through Helium-Leak-Tight Graphene-Based Membranes.Science, 2012; 335 (6067): 442 DOI:10.1126/science.1211694

Chemists Synthesize Artificial Cell Membrane

Neal Devaraj watches as undergraduate student Weilong Li works on a next step in their quest to create an entirely artificial cell. (Credit: Image courtesy of University of California - San Diego)

Chemists have taken an important step in making artificial life forms from scratch. Using a novel chemical reaction, they have created self-assembling cell membranes, the structural envelopes that contain and support the reactions required for life.

Neal Devaraj, assistant professor of chemistry at the University of California, San Diego, and Itay Budin, a graduate student at Harvard University, report their success in theJournal of the American Chemical Society.

"One of our long term, very ambitious goals is to try to make an artificial cell, a synthetic living unit from the bottom up -- to make a living organism from non-living molecules that have never been through or touched a living organism," Devaraj said. "Presumably this occurred at some point in the past. Otherwise life wouldn't exist."

By assembling an essential component of earthly life with no biological precursors, they hope to illuminate life's origins.

"We don't understand this really fundamental step in our existence, which is how non-living matter went to living matter," Devaraj said. "So this is a really ripe area to try to understand what knowledge we lack about how that transition might have occurred. That could teach us a lot -- even the basic chemical, biological principles that are necessary for life."

Molecules that make up cell membranes have heads that mix easily with water and tails that repel it. In water, they form a double layer with heads out and tails in, a barrier that sequesters the contents of the cell.

Devaraj and Budin created similar molecules with a novel reaction that joins two chains of lipids. Nature uses complex enzymes that are themselves embedded in membranes to accomplish this, making it hard to understand how the very first membranes came to be.

"In our system, we use a sort of primitive catalyst, a very simple metal ion," Devaraj said. "The reaction itself is completely artificial. There's no biological equivalent of this chemical reaction. This is how you could have a de novoformation of membranes."

They created the synthetic membranes from a watery emulsion of an oil and a detergent. Alone it's stable. Add copper ions and sturdy vesicles and tubules begin to bud off the oil droplets. After 24 hours, the oil droplets are gone, "consumed" by the self-assembling membranes.

Although other scientists recently announced the creation of a "synthetic cell," only its genome was artificial. The rest was a hijacked bacterial cell. Fully artificial life will require the union of both an information-carrying genome and a three-dimensional structure to house it.

The real value of this discovery might reside in its simplicity. From commercially available precursors, the scientists needed just one preparatory step to create each starting lipid chain.

"It's trivial and can be done in a day," Devaraj said. "New people who join the lab can make membranes from day one."

The National Institute of Biomedical Imaging and Bioengineering supported this work. UC San Diego has filed a patent application on this discovery.

Story Source:

The above story is reprinted from materials provided byUniversity of California - San Diego. The original article was written by Susan Brown.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

---

Journal Reference:

1. Itay Budin, Neal K. Devaraj. Membrane Assembly Driven by a Biomimetic Coupling Reaction. Journal of the American Chemical Society, 2012; 134 (2): 751 DOI:10.1021/ja2076873

Novel energy-storage membrane: Performance surpasses existing rechargeable batteries and supercapacitors

ScienceDaily (Sep. 29, 2011) — A team from the National University of Singapore's Nanoscience and Nanotechnology Initiative (NUSNNI), led by principle investigator Dr Xie Xian Ning, has developed a novel energy-storage membrane.

Electrical energy storage and its management are becoming urgent issues due to climate change and energy shortage. Existing technologies such as rechargeable batteries and supercapacitors are based on complicated configurations including liquid electrolytes, and suffer from difficulties in scaling-up and high fabrication costs. There is also growing public concern and awareness of the impact of traditional energy sources on the environment, spurring a continued search for alternative, green, sustainable energy sources.

Cost-effective and environmentally-friendly

Recognising the issue, Dr Xie and his team have developed a membrane that not only promises greater cost-effectiveness in delivering energy, but also an environmentally-friendly solution. The researchers used a polystyrene-based polymer to deposit the soft, foldable membrane that, when sandwiched between and charged by two metal plates, could store charge at 0.2 farads per square centimeter. This is well above the typical upper limit of 1 microfarad per square centimetre for a standard capacitor.

The cost involved in energy storage is also drastically reduced. With existing technologies based on liquid electrolytes, it costs about US$7 to store each farad. With the advanced energy storage membrane, the cost to store each farad falls to an impressive US$0.62. This translates to an energy cost of 10-20 watt-hour per US dollar for the membrane, as compared to just 2.5 watt-hour per US dollar for lithium ion batteries.

Dr Xie said: "Compared to rechargeable batteries and supercapacitors, the proprietary membrane allows for very simple device configuration and low fabrication cost. Moreover, the performance of the membrane surpasses those of rechargeable batteries, such as lithium ion and lead-acid batteries, and supercapacitors."

The research is supported by grants from the Singapore-MIT Alliance for Research & Technology (SMART), and National Research Foundation. Dr Xie and his team started work on the membrane early last year and took about 1.5 years to reach their current status, and have successfully filed a US patent for this novel invention.

The discovery was featured in Energy & Environmental Science and highlighted by the international journal Nature.

Potential applications: From hybrid vehicles to solar panels and wind turbines

The membrane could be used in hybrid vehicles for instant power storage and delivery, thus improving energy efficiency and reducing carbon emission. Potentially, hybrid cars with the membrane technology could be powered by the energy stored in the membranes in conjunction with the energy provided by fuel combustion, increasing the lifespan of car batteries and cutting down on waste.

The membrane could also be integrated into solar panels and wind turbines to store and manage the electricity generated. Energy provided through these sources is prone to instability due to their dependence on natural factors. By augmenting these energy sources with the membrane, the issue of instability could potentially be negated, as surplus energy generated can be instantly stored in the membranes, and delivered for use at a stable rate at times when natural factors are insufficient, such as a lack of solar power during night-time.

Next Step

The research team has demonstrated the membrane's superior performance in energy storage using prototype devices. The team is currently exploring opportunities to work with venture capitalists to commercialise the membrane. To date, several venture capitalists have expressed strong interest in the technology.

"With the advent of our novel membrane, energy storage technology will be more accessible, affordable, and producible on a large scale. It is also environmentally-friendly and could change the current status of energy technology," Dr Xie said.

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by National University of Singapore, via AlphaGalileo.

Journal References:

Xie Xian Ning. Energy technology: Supersizing a supercapacitor. Nature, 477, 9; 01 September 2011 DOI: 10.1038/477009cXian Ning Xie, Kian Keat Lee, Junzhong Wang, Kian Ping Loh. Polarizable energy-storage membrane based on ionic condensation and decondensation. Energy & Environmental Science, 2011; 4 (10): 3960 DOI: 10.1039/C1EE01841H

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Novel energy-storage membrane: Performance surpasses existing rechargeable batteries and supercapacitors

ScienceDaily (Sep. 29, 2011) — A team from the National University of Singapore's Nanoscience and Nanotechnology Initiative (NUSNNI), led by principle investigator Dr Xie Xian Ning, has developed a novel energy-storage membrane.

Electrical energy storage and its management are becoming urgent issues due to climate change and energy shortage. Existing technologies such as rechargeable batteries and supercapacitors are based on complicated configurations including liquid electrolytes, and suffer from difficulties in scaling-up and high fabrication costs. There is also growing public concern and awareness of the impact of traditional energy sources on the environment, spurring a continued search for alternative, green, sustainable energy sources.

Cost-effective and environmentally-friendly

Recognising the issue, Dr Xie and his team have developed a membrane that not only promises greater cost-effectiveness in delivering energy, but also an environmentally-friendly solution. The researchers used a polystyrene-based polymer to deposit the soft, foldable membrane that, when sandwiched between and charged by two metal plates, could store charge at 0.2 farads per square centimeter. This is well above the typical upper limit of 1 microfarad per square centimetre for a standard capacitor.

The cost involved in energy storage is also drastically reduced. With existing technologies based on liquid electrolytes, it costs about US$7 to store each farad. With the advanced energy storage membrane, the cost to store each farad falls to an impressive US$0.62. This translates to an energy cost of 10-20 watt-hour per US dollar for the membrane, as compared to just 2.5 watt-hour per US dollar for lithium ion batteries.

Dr Xie said: "Compared to rechargeable batteries and supercapacitors, the proprietary membrane allows for very simple device configuration and low fabrication cost. Moreover, the performance of the membrane surpasses those of rechargeable batteries, such as lithium ion and lead-acid batteries, and supercapacitors."

The research is supported by grants from the Singapore-MIT Alliance for Research & Technology (SMART), and National Research Foundation. Dr Xie and his team started work on the membrane early last year and took about 1.5 years to reach their current status, and have successfully filed a US patent for this novel invention.

The discovery was featured in Energy & Environmental Science and highlighted by the international journal Nature.

Potential applications: From hybrid vehicles to solar panels and wind turbines

The membrane could be used in hybrid vehicles for instant power storage and delivery, thus improving energy efficiency and reducing carbon emission. Potentially, hybrid cars with the membrane technology could be powered by the energy stored in the membranes in conjunction with the energy provided by fuel combustion, increasing the lifespan of car batteries and cutting down on waste.

The membrane could also be integrated into solar panels and wind turbines to store and manage the electricity generated. Energy provided through these sources is prone to instability due to their dependence on natural factors. By augmenting these energy sources with the membrane, the issue of instability could potentially be negated, as surplus energy generated can be instantly stored in the membranes, and delivered for use at a stable rate at times when natural factors are insufficient, such as a lack of solar power during night-time.

Next Step

The research team has demonstrated the membrane's superior performance in energy storage using prototype devices. The team is currently exploring opportunities to work with venture capitalists to commercialise the membrane. To date, several venture capitalists have expressed strong interest in the technology.

"With the advent of our novel membrane, energy storage technology will be more accessible, affordable, and producible on a large scale. It is also environmentally-friendly and could change the current status of energy technology," Dr Xie said.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by National University of Singapore, via AlphaGalileo.

Journal References:

Xie Xian Ning. Energy technology: Supersizing a supercapacitor. Nature, 477, 9; 01 September 2011 DOI: 10.1038/477009cXian Ning Xie, Kian Keat Lee, Junzhong Wang, Kian Ping Loh. Polarizable energy-storage membrane based on ionic condensation and decondensation. Energy & Environmental Science, 2011; 4 (10): 3960 DOI: 10.1039/C1EE01841H

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here