Skip to main content

Simple hydrogen storage solution is powered by solar energy



The new reversible hydrogen storage method stores hydrogen atoms in cyclohexane and uses solar energy to release the hydrogen atoms, turning the cyclohexane molecule into benzene. The use of solar energy avoids the need for high temperatures to release the hydrogen. Credit: Li, et al. ©2015 American Chemical Society

By using solar energy to reversibly attach and detach hydrogen atoms on a 6-carbon ring called benzene, scientists have developed a simple and efficient method to store, transport, and release hydrogen potentially on a large scale. The hydrogen storage problem is currently one of the biggest challenges facing the development of hydrogen as a widespread energy carrier, and the researchers hope that the new strategy may lead to a safe and inexpensive solution to this problem.

The scientists, led by Professor Chao-Jun Li and Associate Professor Zetian Mi at McGill University in Montreal, have published a paper on the new  system in a recent issue of the Journal of the American Chemical Society.
As the researchers explain, hydrogen has a very high mass energy density but a very low volumetric energy density. The high mass energy density, which is at least three times higher than that of other chemical fuels, is what makes hydrogen such an attractive energy carrier. However, its low volumetric  under ambient conditions makes it difficult to store large amounts of hydrogen in small spaces. To overcome this problem, hydrogen is often stored at high pressures or low temperatures, but these storage methods present their own challenges.
The hydrogen storage system demonstrated in the new paper works under  and stores the hydrogen in abundant, lightweight, and inexpensive molecules called hydrocarbons. The researchers demonstrated that six  can be added to benzene (C6H6) in a "hydrogenation" process that forms cyclohexane (C6H12), which serves as the hydrogen carrier. In the reverse process, cyclohexane is "dehydrogenated" as the six carbons are removed and available for use in energy storage devices and other applications.
This method of storing hydrogen atoms in hydrocarbons is not new, but because the dehydrogenation process requires a large amount of energy to proceed, current versions always require high temperatures to release the hydrogen.
Since performing the reaction at high temperatures is not suitable for practical applications, here the researchers demonstrated that  can be used to drive the dehydrogenation reaction at ambient temperatures. This process involves using platinum-based nanoparticles as photocatalysts. After absorbing incoming photons, the platinum nanoparticles temporarily donate their photoexcited electrons to the cyclohexane molecules, breaking the carbon-hydrogen bonds and releasing the hydrogen atoms without the need for elevated temperatures.
Tests showed that this photo-driven dehydrogenation process occurs rapidly (within a few seconds), converts 99% of the cyclohexane to benzene, and has a quantum efficiency (H2 produced per photon consumed) of 6.0%, which rivals the current top-performing solar water splitting devices without an external voltage. To start the hydrogenation process, the researchers simply removed the light source, causing the hydrogen atoms to reattach back onto the benzene. Using this method, 97% of the benzene could be converted back to cyclohexane, and the cycle could be repeated.
The researchers expect that this strategy is more suitable for stationary applications—for instance, for storing and transporting energy produced by wind turbines or other alternative  sources—rather than vehicles because of the fact that it requires sunlight to release the hydrogen.
"The applications may include the storage and transport of hydrogen generated from other sources, such as water splitting and water electrolysis, using renewable energies (hydro, wind, nuclear, etc.)," Li told Phys.org.
Taking the next steps forward, McGill University has filed a provisional patent on this technology. In the future, the scientists plan to improve the  storage system by reducing the amount of platinum required in the photocatalysts and developing other less expensive alternatives.
"Our future research is focused on developing cheaper and more earth-abundant metal catalysts, such as iron, and to further increase the quantum efficiency," Li said.

Comments

Post a Comment

Popular posts from this blog

This strange mineral grows on dead bodies and turns them blue

If you were to get up close and personal with Ötzi the Iceman – the 5,000-year-old mummy of a  tattooed ,  deep-voiced  man who died and was frozen in the Alps – you’d notice that his skin is flecked with tiny bits of blue. At first, it would appear that these oddly bluish crystal formations embedded in his skin are from freezing to death or some other sort of trauma, but it’s actually a mineral called  vivianite  (or blue ironstone) and it happens to form quite often on corpses left in iron-rich environments. For Ötzi, the patches of vivianite are  from him resting  near rocks with flecks of iron in them, but other cases are way more severe. According to Chris Drudge at Atlas Obscura , a man named John White was buried in a cast iron coffin back in 1861. During those days, coffins often had a window for grieving family members to peer inside even if the lid was closed during the funeral. Sometime after he was buried, that window broke, allow...
Post a Comment
Read more

It's Official: Time Crystals Are a New State of Matter, and Now We Can Create Them

Peer-review has spoken. Earlier this year , physicists had put together a blueprint for how to make and measure time crystals - a bizarre state of matter with an atomic structure that repeats not just in space, but in time, allowing them to maintain constant oscillation without energy. Two separate research teams managed to create what looked an awful lot like time crystals  back in January,  and now both experiments have successfully passed peer-review for the first time, putting the 'impossible' phenomenon squarely in the realm of reality. "We've taken these theoretical ideas that we've been poking around for the last couple of years and actually built it in the laboratory,"  says one of the researchers , Andrew Potter from Texas University at Austin. "Hopefully, this is just the first example of these, with many more to come." Time crystals  are one of the coolest things physics has dished up in recent months, because they point to a...
Post a Comment
Read more

The Dark Side Of The Love Hormone Oxytocin

New research shows oxytocin isn't the anti-anxiety drug we thought it was. Oxytocin, the feel-good bonding hormone released by physical contact with another person, orgasm and childbirth (potentially encouraging  monogamy ), might have a darker side. The  love drug  also plays an important role in intensifying  negative emotional memories  and increasing feelings of fear in future stressful situations, according to a new study. Two experiments performed with mice found that the hormone activates a signaling molecule called extracellular-signal-related kinases (ERK), which has been associated with the way the brain  forms memories   of fear . According to Jelena Radulovic, senior author on the study and a professor at Northwestern University's medical school, ERK stimulates fear pathways in the brain's lateral septum, the region with the highest levels of oxytocin. Mice without oxytocin receptors and mice with even more oxytocin receptors tha...
Post a Comment
Read more