Rectified Ion Transport in Ultra‐thin Membrane Governed by Outer Membrane Electric Double Layer

Abstract

of main observation and conclusion The outstanding combination of selectivity and permeability observed in ultra-thin nanoporous membranes attracts broad interest from both fundamental research and practical application aspects. It is reported that the asymmetrical ion transport can be realized through the modification of polyelectrolytes on the outer membranes surface. However, the related mechanisms are still unclear which hinders their applications. Herein, we systematically investigate the origin of the ion current rectification in heterogeneously charged ultra-thin nanopores. The calculated results based on the continuity model suggest that, the ion transport across the ultra-thin membrane is dominated by the charge on the outer membrane surface rather than the pore wall. The overlap of electric double layer outside the pore entrance is essential for the ion asymmetric transport. And it accordingly results in the fact that the ion concentration enrichment and depletion effect occurring outside the nanopore orifices governs the high and low ionic conductance states under the applied bias. These features can be regulated by the membrane surface state, which is truly attractive because the surfaces of the outer membrane can be easily modified by experimental approaches. These findings provide the renew inspiration for the design of high-performance 2D nanofluidic devices.

Functional Poly(ionic liquid) Porous Membranes: From Fabrications to Advanced Applications†

“…[ 3‐4 ] Since then, synthetic polymer porous membranes have been extensively found in various practical applications, ranging from water purification and treatment, biopharmaceutical separations to electronics processing. [ 5‐7 ] Despite great advancement of the porous membranes, their primary usages within industry remain in the field of simple filtration and dialysis. It is necessary to consider what the new generation of the membrane is and how we get there.…”

The Optimization of the Transition Zone of the Planar Heterogeneous Interface for High-Performance Seawater Desalination

“…In addition to size-based repulsion, more novel transport mechanisms at nano- or sub-nano scale could be utilized to realize ion sieving or separation, including ion concentration polarization [ 35 , 36 ], asymmetric ion transport [ 37 , 38 , 39 ] and heterogeneous membrane structure [ 40 , 41 , 42 , 43 , 44 ]. These phenomena can exist at scales larger than 1 nm, which effectively enhance the permeability while maintaining the ion rejection.…”

Anomalous temperature dependence of ion transport under osmotic pressure in graphene oxide membranes

“…Synthetic nanoporous membranes have attracted broad interest because they boost the development of DNA sequencing [1][2][3], chemical sensing and delivery [4][5][6], ion filtration [7,8], pervaporation [9][10][11][12], energy conversion [13][14][15][16] and nanoelectronics [17][18][19]. The interest stems from the unique mass transport properties very different from the counterpart of the macro scale [20,21]. Particularly, the newly emerged 2D materials are considered to be candidates for next generation high-performance membrane materials due to their atomic thickness, excellent thermal and chemical stability, outstanding flexibility and solution processability [22].…”