Enhancing ion transport in pressure-driven nanofluidic systems for energy harvesting

Abstract

In this work, we propose a new design to enhance ion transport in pressure-driven nanofluidic systems for energy harvesting. The proposed system uses two counter-charged nanochannels, i.e., one of the channels is negatively charged while the other one is positively charged. Under a pressure gradient, cations and anions move through negatively and positively charged channels, respectively, in different directions and contribute to the streaming current. Molecular dynamics simulations are employed to study the effects of surface charge density, channel height, and pressure gradient on the streaming current. Compared with the traditional system, where the nanochannel is negatively charged, the streaming current in the proposed system can be enhanced by a factor up to 6.6. In addition to the involvement of both cations and anions, the enhanced current in the proposed system is caused by the strengthened ionic fluxes due to relatively low-energy barriers for ions entering the channels.