Ionic Liquid Filled Single-Walled Carbon Nanotubes for Flow-Induced Energy Harvesting

Harvesting flow-induced energy for powering nanoelectromechanical systems offers much promise for nanotechnology. Motivated by the electric eel, which is capable of generating considerable electric shocks with highly selective ion channels and pumps on its cell membrane, herein, we employed molecular dynamics simulations to investigate the flow-induced energy harvesting through flowing three kinds of imidazolium-based ionic liquids (ILs) over single-walled carbon nanotubes (SWCNTs) with diameters varied from 1.22 to 4.07 nm at temperatures ranging from 300 to 375 K. The results show that ILs inside a SWCNT with a diameter of 3.39 nm flow at a speed of ∼19 m/s resulting in a considerable flow-induced voltage (FIV) up to 2.22 μV, and the maximal FIVs increase from 1.91 to 2.34 μV as the diameter of the SWCNT varies from 1.22 to 4.07 nm at 300 K. Further analysis shows that this FIV arises from the free charge carriers on the inner surface of SWCNTs drifting along the flow direction of ILs under the drag of the Coulomb field, and the FIV increases to saturation with increased average flow velocity of ILs which is caused by the balance between internal resistance arising from the ILs and SWCNTs and the external driving force. This work also demonstrates an advanced equation to appropriately and effectively calculate the FIV of flowing ILs inside SWCNTs on the nanoscale which involves the effect of Coulomb field present in ILs on the free charge carriers of the SWCNT inner surfaces and the characteristic of Coulomb interactions. Moreover, the dependence of FIV on anion species, temperature, and average flow velocity of ILs is also investigated.