Making Water Do the Splits

It's hard to imagine a greener way to power the planet than using solar power to turn water into hydrogen gas. This clean fuel can be piped through fuel cells to produce electricity and then recombined with oxygen to yield water as a waste product. Sunlight doesn't break water molecules apart on its own, however, which is why Earth is covered with oceans. So researchers have spent decades searching for catalysts to help it along. And new work by researchers in Virginia takes a key step toward that goal.

A good solar catalyst has to be a jack of many trades. It must absorb high levels of solar energy, move the resulting electrons to a catalytic site where they can split water molecules into hydrogen and oxygen atoms, and finally stitch a new bond between two hydrogen ions to generate hydrogen gas. On top of that, the catalyst must be cheap and not generate any unwanted byproducts that would prevent the reaction from working over and over again.

No water-splitting catalyst has come close to meeting all these challenges. One major stumbling block has been that two electrons are needed to turn hydrogen ions into hydrogen gas. Previous approaches for turning water to hydrogen have created catalysts only capable of dealing with one electron at a time, largely because electrons tend to repel each other.

more from Science magazine