Voltage-Gated Ions Sieving through 2D MXene Ti₃C₂T_<i>x</i> Membranes

We report a nanochanneled Ti3C2Tx MXene membrane that enables an efficient controlled rejection/permeation of inorganic ions and organic dye molecules under applied electrical potential. When a negative electrical potential (−0.6 V) is applied to the Ti3C2Tx MXene membrane under only osmotic pressure, the rejection of inorganic salt (NaCl or MgSO4) through the membrane is enhanced. In contrast, applying a positive potential inhibits the rejection through electrostatic repulsion between charged MXene layers and inorganic cations in solution. The rejection rates of Ti3C2Tx membranes are also tested in a flow-through system. MXene membranes as thin as 100 nm show a high rejection rate above 97.9 ± 1.0% for methylene blue dye molecules. Similar to inorganic salts, application of negative or positive voltages increases and decreases, respectively, the transport of molecules through Ti3C2Tx membranes. The voltage gated rejection through electronically conductive membranes is demonstrated as a promising alternative to improve rejection of inorganic salts and organic molecules.