A team at the University of Wisconsin-Madison made crystals of zinc oxide that, when immersed in water, absorb vibrations and develop areas of strong negative and positive charge. These charges rip apart nearby water molecules, releasing hydrogen and oxygen gas.
Xu and colleagues generate hydrogen using a new variation on piezoelectric crystals – materials that generate a voltage when strained and which are being investigated as a way to generate electricity from movement.
The new crystals, however, are designed to be submerged, so the charge they generate instead pulls apart water molecules to release hydrogen and oxygen gas, a mechanism Xu’s team calls the piezoelectrochemical effect.
Xu and colleagues grew thin microfibers of highly flexible zinc oxide crystals that flex when subjected to vibration, for example due to sound waves. They showed that ultrasonic vibrations under water cause the fibres to bend between 5 and 10 degrees at each end, creating an electrical field with a high enough voltage to split water and release oxygen and hydrogen.
Read more at New Scientist