Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


The presence of oxygen on carbon nanotubes enhances interaction with ammonia


Discovery could help in the development of sensors against chemical threats

Single-walled carbon nanotubes (SWNTs), which could play an important role in developing sensors against chemical threats, have enhanced interaction with ammonia because of the presence of oxygen groups on the nanotubes, researchers at Temple University have discovered.

Their findings, "Sensitivity of Ammonia Interaction with Single-Walled Carbon Nanotube Bundles to the Presence of Defect Sites and Functionalities," are reported online July 8 in the Journal of the American Chemical Society.

Eric Borguet, Ph.D., associate professor of chemistry at Temple and the study’s lead author, said scientists have shown that in using nanotubes for sensors, their conductivity can be changed by the presence of ammonia.

"Theorists have tried for a long time to explain this interaction, and their calculations have typically shown that the interaction between the carbon nanotubes and ammonia is very weak, and in fact, very few ammonia molecules would stick to the nanotubes at room temperature," said Borguet.

But, he said, the theorists are studying pure nanotubes--often referred to as "perfect" nanotubes--with no oxygen.

Through the use of infrared spectroscopy, Borguet and his collaborators believe they are the first to reveal that the SWNT purification process, which introduces oxygen to the nanotubes, changes the interaction with chemical species such as ammonia.

"It is no longer pure carbon; there are oxygen-containing groups on the purified nanotubes," said Borguet. "And it is the presence of those groups that enhances the interaction between the nanotubes and the ammonia molecules at any temperature.

"We take the nanotubes and heat them up to 500 degrees Kelvin and then cool them down to 94 degrees Kelvin, and we see ammonia sticking, but as we go higher and higher in temperature, the ammonia signal is going down," said Borguet.

"One of the things that is happening as we heat to higher and higher temperatures is we are driving off the oxygen-containing functionality," added Borguet. "Once that oxygen-containing functionality is gone, ’poof,’ the ability of the ammonia to stick is gone. But if we re-expose the SWNTs to room temperature and ambient air, the ability to interact comes back."

Borguet said the researchers were not able to detect the oxygen after exposure to air, so the nanotubes may be reoxidizing at a very small level.

He also emphasized that although they are unable to detect the ammonia sticking to the SWNTs at higher temperatures, the lack of detection may be the result of using the infrared spectroscopy technique.

"There may be another technique with a higher sensitivity that can detect the presence of ammonia," Borguet said. "We can’t say there is no ammonia, but if there is, it is below our group’s detection capability."

Borguet said that this discovery of oxygen impacting the interaction of ammonia with the SWNTs could eventually be important in developing small sensors for Homeland Security.

"Ultimately, you’d like to make a chemical nose, a device that can distinguish between chemicals which might have different hazards associated with them," he said. "You’d like to be able to identify the chemicals and what type of concentration might be present.

"These finding are a step in the right direction," Borguet added. "This could be an important discovery because theorists have all been calculating using ’perfect’ nanotubes, but the experiments are not being carried out on ’perfect’ nanotubes.

"The theorists can no longer ignore that there is going to be oxygen-containing functionality when looking at the effects of these nanotubes in the future."

Preston M. Moretz | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Don't Give the Slightest Chance to Toxic Elements in Medicinal Products
23.03.2018 | Physikalisch-Technische Bundesanstalt (PTB)

nachricht North and South Cooperation to Combat Tuberculosis
22.03.2018 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Space observation with radar to secure Germany's space infrastructure

Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.

The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

New solar solutions for sustainable buildings and cities

23.03.2018 | Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

Latest News

Don't Give the Slightest Chance to Toxic Elements in Medicinal Products

23.03.2018 | Life Sciences

Sensitive grip

23.03.2018 | Materials Sciences

No compromises: Combining the benefits of 3D printing and casting

23.03.2018 | Process Engineering

Science & Research
Overview of more VideoLinks >>>