Researchers at China’s Nanjing University of Aeronautics and Astronautics have discovered that dragging saltwater over a piece of graphene can create electricity. The study was published in the journal of Nature Nanotechnology .
In their tests, the researchers used single drops of sea water on strips of monolayer graphene and then dragged them around. The results where a knock out. Not only did it result in the generation of electricity, but additional drops or increasing the velocity of dragging improved the voltage.
When a saltwater drop sits still on top of a strip of graphene, all charge is redistributed symmetrically on both sides of the drop, leaving zero net potential difference between them.
The moving saltwater generated voltage—30mV—enough to allow the team to use it as part of a handwriting sensor and as part of an energy harvesting device. Moving the drop caused the distribution to become unbalanced—electrons are desorbed at one end of the drop and absorbed at the other, generating the voltage.