Solving a solar energy mystery

For Tom Meyer, the solution to storing solar energy began 40 years ago in the mystery of a molecule.

“When molecules absorb light, they form excited states in which the electrons are rearranged and become more accessible,” he said. “The key was to take advantage because, at that point, with light absorption, energy conversion has occurred with the sun’s energy stored in the molecule.”

Though it was just one piece of information Meyer would need to uncover in the coming years, it was this insight into basic chemistry that eventually brought about what might become a significant breakthrough in solar energy: the ability to harness the sun’s energy for use even after it sets by converting its energy into fuels.

“You have an idea like this and then you go into the lab and try it out,” said, Meyer, Arey Distinguished Professor of Chemistry. “In this case, it actually worked.” (See here for more on the science behind the breakthrough.)

‘It’s all about timing’

Shortly after he arrived at Carolina in 1968, Meyer began collecting clues in pursuit of a mystery: how to mimic natural photosynthesis in converting and storing the sun’s energy as fuel.

That’s a long time to follow a thread, but Meyer was patient.

Key members of the research group had come and gone, and so had funding. Each step of the scientific process brought another piece to the puzzle. But, finally, with UNC’s Energy Frontier Research Center and a partnership with a group at N.C. State, “the talents we needed all fell into place.”

They had figured out light absorption, water oxidation and how to make molecules that split water and separate the electrons needed to generate hydrogen fuel. But the electrons couldn’t be freed quickly enough. Meyer wanted to try a “core-shell technique” with a thin coating of titanium dioxide on the outside of a conducting material that would allow the electrons to move more rapidly and allow time to strip electrons and protons from water to make oxygen.

To refine this technique, the Parsons group at N.C. State had something the Carolina group did not: the machine to make the layers Meyer needed to create the core-shell coating for the reactive molecules.

“All these pieces had to be in place, and without them, and without that capability, we couldn’t have done it,” he explained.

Meyer is a big believer in the right team: with chemists, physicists and materials scientists involved, difficult research problems can be addressed quickly with access to a broad spectrum of capabilities. Teamwork brings together scientists who create new materials with those who measure properties and those who make the devices to integrate it all.

It’s an object lesson in how to use the strengths of basic science to improve things and make changes rapidly, Meyer said. “That’s at the heart and soul of all this: if you can’t integrate and respond quickly, you’re not in the game.”

It’s all about timing, Meyer said. With the last piece of the puzzle in place, the team began repeatedly to produce the reaction they were looking for – they had made it happen.

“There was a feeling of, at last!” he said.

Read more from the University Gazette story.

Published January 31, 2014.