Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Titania nanotubes make supersensitive hydrogen sensors

30.07.2003


Titania nanotubes at 200 nanometer size. Credit: Penn State, Craig Grimes


Titania nanotubes at 250 nanometer size. Credit: Penn State, Craig Grimes


Titania nanotubes are 1500 times better than the next best material for sensing hydrogen and may be one of the first examples of materials properties changing dramatically when crossing the border between real world sizes and nanoscopic dimensions, according to a Penn State materials scientist.

"Historically, we have viewed sensor technology and enhancements from the point of view of surface area," says Dr. Craig A. Grimes, associate professor of electrical engineering and materials science and engineering. "The principle in play in titania nanotubes is not surface area, but connectivity of the tiny tubes and we see an incredible change in electric resistance."

Hydrogen entering an array of titania nanotubes flows around all the surfaces, but it also splits into individually charged atoms and permeates the surface of the nanotubes. These hydrogen ions provide electrons for conductivity. The change in conductance signals that hydrogen, above the background level, is present.



"Many researchers have tried to use carbon nanotubes as gas sensors, but they do not work very well," says Grimes. "Titania has really great sensitivity and a nice response."

The Penn State researcher notes that the material can be made by the mile and is very cheap as well as very sensitive. The material is also not used up when sensing hydrogen, but once the gas clears from the tubes, can be used again.

Sensors for hydrogen are used in industrial quality control in food plants and as weapons against terrorism. In a bakery, for example, sensors sniff hydrogen and measure temperature to determine when goods are done. Hydrogen sensors are also used in combustion systems of automobiles to monitor pollution and may be used as diagnostic tools to monitor certain types of bacterial infections in infants.

Grimes, working with Oomman K. Varghese, Dawai Gong, Maggie Paulose and Keat G. Ong, postdoctoral fellows, and Dr. Elizabeth C. Dickey, associate professor of materials science and engineering, looked at nanotubes of 22 and 76 nanometer diameters. They reported their findings in the Aug. 1 issue of Sensors and Actuators B: Chemical and in a recent issue of Advanced Materials.

The 22 nanometer and 76 nanometer tubes differ in surface area by a factor of two, but the response to hydrogen of the smaller tubes is 200 times more sensitive than the 76 nanometer tubes.

"The sensitivity comes from the nanoarchitecture, not the surface area," says Grimes.

The researchers suggest that "the hydrogen molecules get dissociated at the titania surface, diffusing into the titania lattice, and act as electron donors." The researchers believe that this mechanism makes the nanotubes sensitive to hydrogen.

One problem often found in sensors is that they become poisoned, either by the gas they test, or by other gases in the atmosphere, and no longer operate. The researchers tested the titania nanotubes with carbon dioxide, carbon monoxide, ammonia and oxygen finding little interference.

"Our results show that titania nanotube sensors can monitor hydrogen levels from 1 part per million to 4 percent," says Grimes. "Titania nanotubes can be used successfully as hydrogen sensors."

Andrea Elyse Messer | EurekAlert!
Further information:
http://www.psu.edu

More articles from Materials Sciences:

nachricht Flying: Efficiency thanks to Lightweight Air Nozzles
23.10.2017 | Technische Universität Chemnitz

nachricht Strange but true: Turning a material upside down can sometimes make it softer
20.10.2017 | Universitat Autonoma de Barcelona

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>