Molecular thermal motion harvester for electricity conversion via triboelectrification

Molecular thermal motion is ubiquitous, and in theory, the energy of which could be converted into electrical energy. However, not until recently, the conversion of molecular thermal motion into electricity was demonstrated feasible for the first time, through the interaction of piezoelectric nano-wires and liquid molecules. However, the electricity output was very low. In this work, we developed a new system capable of converting molecular thermal motion into electricity via the triboelectric properties of polymer materials and achieved significantly higher power output. Nylon 66 and polystyrene possess different triboelectric charge densities and are selected as substrate layers. An aqueous solution of water-soluble polymer such as PVA was placed between nylon 66 and polystyrene layers. The thermal motion of liquid molecules and the Brownian motion of water-soluble polymers in solutions lead to interaction/friction with the triboelectric substrate layers and cause the migration of electrons and charges between nylon 66 and polystyrene layers. A much higher and stable electrical output with a voltage of 29.7 mV and a current of 60.4 μA was achieved, which is tens of thousands of times greater than that from our earlier work, which was based on piezoelectric effect.