Rectified Ion Transport Through 2D Nanofluidic Heterojunctions

Nacre-mimetic 2D nanofluidic architectures emerge as a splendid platform for both fundamental research and practical application of the novel ionic and molecular transport phenomena on nano- and sub-nanoscale. So far, it is challenging to endow the 2D nanofluidic systems with asymmetric transport properties and tunable selectivity. Herein, a heterogeneous 2D nanofluidic membrane is fabricated by sequential deposition of negatively and positively charged graphene oxide (GO) nanosheets, and the rectified salt ion transport properties therein are investigated. A simple resistance model is proposed to explain the ionic current rectification. Intriguingly, by changing the relative portion of the two oppositely charged GO parts, the membrane selectivity can be modulated from perfect cation-selectivity to anion-selectivity. The heterogeneous GO membrane may find potential applications for water treatment and energy conversion.