Researchers show applied electric field can significantly improve hydrogen storage properties

Feb 02, 2010
This image illustrates that an applied electric field polarizes hydrogen molecules and the substrate, inducing hydrogen absorption with good thermodynamics and kinetics. Credit: Image courtesy of Qian Wang, Ph.D./VCU.

An international team of researchers has identified a new theoretical approach that may one day make the synthesis of hydrogen fuel storage materials less complicated and improve the thermodynamics and reversibility of the system.

Many researchers have their sights set on hydrogen as an alternative energy source to fossil fuels such as oil, natural gas and coal that contain carbon, pollute the environment and contribute to global warming. Known to be the most abundant element in the universe, hydrogen is considered an ideal energy carrier - not to mention that it's clean, environmentally friendly and non-toxic. However, it has been difficult to find materials that can efficiently and safely store and release it with fast kinetics under ambient temperature and pressure.

The team of researchers from Virginia Commonwealth University; Peking University in Beijing; and the Chinese Academy of Science in Shanghai; have developed a process using an electric field that can significantly improve how is stored and released.

"Although tremendous efforts have been devoted to experimental and theoretical research in the past years, the biggest challenge is that all the existing methods do not meet the Department of Energy targets for materials. The breakthrough can only be achieved by exploring new mechanisms and new principles for materials design," said Qiang Sun, Ph.D., research associate professor with the VCU team, who led the study.

"We have made such an attempt, and we have proposed a new principle for the design of which involves materials with low-coordinated, non-metal anions that are highly polarizable in an applied electric field," he said.

"Using an external electric field as another variable in our search for such a material will bring a hydrogen economy closer to reality. This is a paradigm shift in the approach to store hydrogen. Thus far, the efforts have been on how to modify the composition of the storage material. Here we show that an applied electric field can do the same thing as doped metal ions," said Puru Jena, Ph.D., distinguished professor in the VCU Department of Physics.

"More importantly, it avoids many problems associated with doping metal ions such as clustering of metal atoms, poisoning of metal ions by other gases, and a complicated synthesis process. In addition, once the electric field is removed, hydrogen desorbs, making the process reversible with fast kinetics under ambient conditions," he said.

The team found that an external electric field can be used to store hydrogen just as an internal field can store hydrogen due to charge polarization caused by a metal ion.

"This work will help researchers create an entirely new way to store hydrogen and find materials that are most suitable. The challenge now is to find materials that are easily polarizable under an applied electric field. This will reduce the strength of the needed for efficient storage," said Jena.

Explore further: Faster switching helps ferroelectrics become viable replacement for transistors

More information: The research is published online in the Early Edition of the Proceedings of the National Academy of Sciences and will be highlighted in the front section of the print edition, 'In this Issue.'

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Parsec
5 / 5 (1) Feb 02, 2010
I would hate to think that losing power would cause all the hydrogen in my car's hydrogen tank to be 'desorbed'. In an accident, a large cloud of hydrogen combined with a spark, would cause rapid vehicular disassembly along with its passengers.

I would be a lot more comfortable with materials that 'desorbed' on the application of an electric field, rather than depending on an external field to be stable. Far too much possibility of an oops factor.
gmurphy
not rated yet Feb 02, 2010
what sort of energy densities are attainable using this approach?
antialias
not rated yet Feb 03, 2010
I would hate to think that losing power would cause all the hydrogen in my car's hydrogen tank to be 'desorbed'.


Check out crash test videos of hydrogen tanks and gasoline tanks.
http://evworld.co...ryid=482

Hydrogen is relatively benign when it escapes - even when it catches fire. When it doesn't catch fire you don't get much of a cloud because it is very bouyant and quickly escapes upwards (as opposed to gasoline that pools and remains flammable/explosive for a very long time)

If a tank using a field would suddenly lose power you'd just have to engineer a rated break point. No biggie.

I know which car I'd rather crash in. Hydrogen, for sure.

Nik_2213
not rated yet Feb 03, 2010
By analogy with storing acetylene in eg acetone on bricks/pumice, perhaps hydrogen would take to electrets ??

http://en.wikiped...Electret
gwrede
1 / 5 (1) Feb 04, 2010
@antialias: Then you'd better not crash in an underground parking garage.
antialias
not rated yet Feb 05, 2010
So? Even underground parking garages have vents? The gas will escape to the outside. Even in the unlikley even that you have (stupidly) built an airtight, domed garage the gas that will be captured in the dome will then be at normal pressure. Putting a flame to that will not cause much of an explosion (remember your chemistry class? Hydrogen under 1ATM pressure just goes 'phut' when you light it.)

And seriously: when was the last time you heard of someone crashing a car in an underground garage so hard that the tank ruptured? The only time I ever saw that was in a Bond movie.

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