Energy

Broad-spectrum solar breakthrough could efficiently produce hydrogen

Broad-spectrum solar breakthro...
OSU scientists have created a new photocatalytic molecule that can generate hydrogen more efficiently using the entire visual spectrum of light
OSU scientists have created a new photocatalytic molecule that can generate hydrogen more efficiently using the entire visual spectrum of light
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OSU scientists have created a new photocatalytic molecule that can generate hydrogen more efficiently using the entire visual spectrum of light
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OSU scientists have created a new photocatalytic molecule that can generate hydrogen more efficiently using the entire visual spectrum of light

A new molecule developed by Ohio State University scientists can harvest energy from the entire visible spectrum of light, bringing in up to 50 percent more solar energy than current solar cells, and can also catalyze that energy into hydrogen.

Hydrogen is viewed by many folks, particularly in Japan and Korea, as the clean-burning fuel that might power our vehicles in a low-emissions future. One way to produce hydrogen is to split it out of water. This is typically done by splitting water molecules into hydrogen and oxygen using electricity, but a potentially simpler and more efficient way to do it may be through photocatalytic water splitting, which uses light itself as the energy source instead of electricity, removing electricity production from the process altogether.

Nobody has yet managed to commercialize photocatalytic hydrogen production, but it's a hot area of research, and this OSU team claims it's discovered one of the most efficient photocatalytic molecules to date.

The molecule has shown a unique ability to use light from right across the visible spectrum. Where most previous photocatalysts have focused on high-energy ultraviolet wavelengths, this one can capture energy from ultraviolet, all the way through the visible spectrum and well into the near infrared range, meaning it can absorb up to 50 percent more solar energy than current solar cells.

Many previous attempts, the researchers say, have also lost efficiency due to their use of two or more molecules in the catalyst. Energy is lost in these systems as these molecules exchange electrons – not a problem with OSU's single-molecule solution.

The new photocatalyst in question is a form of the element rhodium. The researchers tested it in a lab by shining LED light onto an acid solution containing the active molecule, and found that hydrogen gas was released.

“What makes it work is that the system is able to put the molecule into an excited state, where it absorbs the photon and is able to store two electrons to make hydrogen,” says professor Claudia Turro, director of the OSU Center for Chemical and Biophysical Dynamics. “This storing of two electrons in a single molecule derived from two photons, and using them together to make hydrogen, is unprecedented.”

There are still problems to be worked out before this becomes a commercially viable means of producing clean fuel. The main one is that rhodium is rare and expensive; Turro says the team is trying to figure out how to build it from less expensive materials and make it last longer. But this research certainly gets photocatalytic hydrogen production one step closer to being a reality.

The research has been published in Nature Chemistry.

Source: Ohio State University

14 comments
Mzungu_Mkubwa
So putting the issue of large-scale hydrogen production from our precious water resource aside, this is a huge thing for solar electric generation, if the boost is truly that large of a percentage! Isn't the best solar efficiency currently somewhere just below 30%? This 50% boost would then mean nearly 45% total efficiency for solar cells, right? Sounds like the true boon for clean energy there!
Catweazle
"our precious water resource aside" --- Really? Over 70% of the Earth's surface is covered in water to a depth of 3.7 kilometres, about 1.3 billion cubic kilometres. I would hardly call that a scarce resource. Also, remember that after the hydrogen is burned, it reverts to water, so the total quantity of water is conserved in any case.
Lawrence Smith
Burn our clean water and converting it to energy results in the total loss of water(Hydrogen). It does not go back to H20 if it is energy, If splitting water goes large scale it will be the destruction of our planet. Show me anywhere we convert Hydrogen and Oxygen back to water other than a Fuel Cell, and there is still a loss of Hydrogen there.
EBM
To MM and Larry S 2H2 + O2 -> 2H2O + energy. Pretty basic chemistry regarding H2 energy economy known for decades
George Tziviskos
@Lawrence Smith, here is one industrial application, other than fuel cells, that uses massive amounts of hydrogen and converts them to water: Metal sintering. I’m sure there are many others. Most processes that use hydrogen would either recycle it, or burn it before releasing it to the atmosphere. The former does not require continuous production of hydrogen (other than replenishing leakage losses), and the latter produces water. Hydrogen is one of the most renewable and environmentally-friendly energy storage solutions.
DaveWesely
@Lawrence - Burning H2 in an ICE engine is not very energy efficient. But most of the output is H2O. In a fuel cell, all of the output is H2O. (2H2 + O2 => 2H2O) There is no molecular loss, no planetary destruction in either case.
bwana4swahili
@Lawrence Smith I would really suggest you take a chemistry class. Burning hydrogen and hydrogen used in fuel cells result in water as the end result; no net loss of water in either case. Yes, hydrogen is an excellent source of clean energy for vehicles, home heating/cooling and industry if the safety problems can be overcome.
FrancisChetcuti
Hydrogen is my preferred future transport fuel for the simple reason that it will replace the current toxic carbon producing energy but sustaining a longer mileage duration in a desert environment Also self sustained producing hydrogen will be feasible especially shipping movement where water is continuously available and the sun does the rest.
Douglas Rogers
The most economical photovoltaics are running around 15% efficiency.
PAV
I wonder if a Cobalt based molecule would be able to replace the Rhodium molecule.