Scientists closer to developing material capable of splitting water for better storage of solar energy

Experiments needed to see if the material works in the real world

Scientists have edged closer to uncovering a new class of materials, called halide double perovskites, which could be capable of splitting water - something that could aid the storing of solar energy.

That's according to researchers behind a newly published paper in Applied Physics Letters, from AIP Publishing.

"Solar energy is clean and abundant. But when the sun isn't shining, you must store the energy in batteries or through a process called photocatalysis, in which solar energy is used to make fuels," explained the researchers behind the discovery.

"In photocatalytic water splitting, sunlight separates water into hydrogen and oxygen. The hydrogen and oxygen can then be recombined in a fuel cell to release energy."

While the researchers have experimented with many photocatalytic materials before, so far, no photocatalytic material for general water splitting has become commercially available. However, the new class of materials may have just the right properties to split water, the scientists claimed.

"If we can come up with a material that can be useful as a water-splitting photocatalyst, then it would be an enormous breakthrough," said Feliciano Giustino, a co-author on the paper.

Using supercomputers to calculate the quantum energy states of four halide double perovskites, Giustino found that the photocatalytic materials called Cs2BiAgCl6 and Cs2BiAgBr6 are promising because they absorb visible light much better than previous methods. They also generate electrons and 'holes' (the positively charges absence of electrons) that have sufficient energy to split water into hydrogen and oxygen.

Very few other materials have all these features at once, Giustino said: "We can't say this will work for sure, but these compounds seem to have all the right properties."

The next step, the researchers said, is for experimentalists to see if the material works in the real world as well as predicted. In the meantime, they are using their computational techniques to explore whether these double perovskites have properties useful for other applications like light detectors.