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 Breaking bad metals with neutrons
16.01.2018 | DOE/Argonne National Laboratory

nachricht White graphene makes ceramics multifunctional
16.01.2018 | Rice University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

White graphene makes ceramics multifunctional

16.01.2018 | Materials Sciences

Breaking bad metals with neutrons

16.01.2018 | Materials Sciences

ISFH-CalTeC is “designated test centre” for the confirmation of solar cell world records

16.01.2018 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>