Tiny piezoelectric strands create electricity from molecular motion

The electricity-generating mechanism of the molecular thermal motion harvester. Image: Yucheng Luan and Wei Li.

Wave energy technology is a proven source of power generation, but power is also inherent in every molecule of liquid on earth, even when the liquid is at rest. At the molecular scale, atoms and ions are always moving. If this nanoscale movement can be harvested, it could be a big source of energy.

“There are vast amounts of air and liquid on the earth, and their successful harvesting could produce a gigantic amount of energy for society,” said Yucheng Luan from East Eight Energy Co. in China.

Together with collaborators, Luan has tested a molecular energy harvesting device that can capture the energy from the natural motion of molecules in a liquid. This work, reported in a paper in APL Materials, showed that molecular motion can be used to generate a stable electric current.

To create the device, Luan and his collaborators submerged nanoarrays of a piezoelectric material in liquid, allowing the movement of the liquid to move the piezoelectric strands like seaweed waving in the ocean. In this case, however, the movement is on the invisible, molecular scale, and the strands are made of zinc oxide. The zinc oxide material was chosen for its piezoelectric properties, which means that when it waves, bends or deforms under motion, it generates an electric potential.

“As a well-studied piezoelectric material, zinc oxide can be easily synthesized into various nanostructures, including nanowhiskers,” Luan said. “A nanowhisker is a neat and orderly structure of many nanowires, similar to the bristles on a toothbrush.”

These energy harvesters could be used to power nanotechnologies like implantable medical devices, or they could be scaled up to full-size generators for kilowatt-scale energy production. One key design feature of the device is that it doesn’t rely on any external forces, enhancing its potential as a game-changing clean energy source.

“Molecular thermal motion harvester devices do not need any external stimulation, which is a big advantage compared with other energy harvesters,” Luan explained. “At present, electrical energy is mainly obtained by external energy, such as wind energy, hydroelectric energy, solar energy and others. This work opens up the possibility of generating electrical energy through the molecular thermal motion of liquids, from the internal energy of the physical system that is essentially different from ordinary mechanical motion.”

The researchers are already working on the next phase of their design to improve the energy density of the device by testing different liquids and different high-performing piezoelectric materials. They are also exploring new device architectures and looking at enlarging the device.

“We believe this novel kind of system will become an indispensable way for human beings to obtain electrical energy in the near future,” said Luan.

This story is adapted from material from the American Institute of Physics, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.

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