Solar Fuels – Storing Sunlight in Chemical Bonds
Solar Fuels are created by using light to split water into hydrogen and oxygen. These elements can be used as fuels via pure hydrogen (fed to a fuel cell) or combined with carbon to create ‘green’ hydrocarbons.
Fuels are desirable because their chemical bonds give us high energy density. Nature creates fuels by using sunlight to split water into hydrogen and oxygen during photosynthesis. Human scientists have been able to do this effectively for several years now. The challenge has been understanding details of the multi-step process.
Cal Tech Researchers See Iron as Key to Hydrogen
From a Cal Tech press release:
In 2014, researchers in the lab of Harry Gray, Caltech’s Arnold O. Beckman Professor of Chemistry, developed a water-splitting catalyst made of layers of nickel and iron. However, no one was entirely sure how it worked. Many researchers hypothesized that the nickel layers, and not the iron atoms, were responsible for the water-splitting ability of the catalyst (and others like it).
To find out for sure, Bryan Hunter (PhD ’17), a former fellow at the Resnick Institute, and his colleagues in Gray’s lab created an experimental setup that starved the catalyst of water. “When you take away some of the water, the reaction slows down, and you are able to take a picture of what’s happening during the reaction,” he says.
Those pictures revealed the active site of the catalyst — the specific location where water is broken down into oxygen — and showed that iron was performing the water-splitting reaction, not nickel.
“Our experimentally supported mechanism is very different than what was proposed,” says Hunter, first author of a paper published February 6 in Joule, a journal of sustainable-energy research, describing the discovery. “Now we can start making changes to this material to improve it.”
Gray, whose work has focused on solar fuels for decades, says the discovery could be a “game changer” for the field.
Trapping an Iron(VI) Water Splitting Intermediate in Nonaqueous Media. Joule, 2018: 10.1016/j.joule.2018.01.008
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