Researchers find new method to tap energy during day for use at night

15 January 2014 (Last Updated January 15th, 2014 18:30)

Researchers at the Energy Frontier Research Center of the University of North Carolina-Chapel Hill (UNC-Chapel Hill) have developed a new device that converts the sun’s energy into hydrogen fuel and stores it for use at nights.

Meyer

Researchers at the Energy Frontier Research Center of the University of North Carolina-Chapel Hill (UNC-Chapel Hill) have developed a new device that converts the sun's energy into hydrogen fuel and stores it for use at nights.

The new solution, known as 'dye-sensitized photoelectrosynthesis cell (DSPEC)' will address the fundamental problems of storing power for later use and using it even after the sun goes down.

The cell will use the sun's energy to split water into its atomic-level component parts including hydrogen fuel and the byproduct oxygen.

After the split, hydrogen is sequestered and stored, and can used as fuel, generating only water as waste that can be recycled to be split again, while oxygen is released into the air.

UNC College of Arts and Sciences Professor of Chemistry Tom Meyer, who led the research, said it is very difficult to split water as four electrons is required to be taken away from two water molecules, transfer them somewhere else, make hydrogen and then keep the hydrogen and oxygen separated.

"How to design molecules capable of doing that is a really big challenge that we've begun to overcome," said Meyer.

Meyer's design is composed of basic components: a molecule called a chromophore-catalyst assembly that absorbs sunlight and then begins the catalyst to rip electrons away from water; and a nanoparticle, to which many chromophore-catalyst assemblies are attached, is part of a film that shuttles away electrons.

"How to design molecules capable of doing that is a really big challenge that we've begun to overcome."

The design did not work smoothly, and hence Meyer turned to NCSU's Parsons group to use a method of coating the nanoparticle with a thin layer of titanium dioxide and the researchers then found that the nanoparticle could carry away electrons quickly, with the freed electrons available to make hydrogen.

Additionally, the researchers have also found the way to build a protective coating that keeps the chromophore-catalyst assembly attached to the nanoparticle.

The researchers conclude that Meyer's new system can turn the sun's energy into fuel with almost no external power, with electrons flowing freely through the nanoparticle and the tether stabilized.


Image: Tom Meyer, Arey Distinguished Professor of Chemistry at UNC's College of Arts and Sciences. Photo: courtesy of University of North Carolina-Chapel Hill.

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