Simultaneous voltage-gated control of ion and water transport in Zr4-Ti3C2Tx nanochannel membranes

Controlling water and ion transport across nanoconfined channels is essential for natural biological processes and crucial for breakthroughs in diverse scientific and technological fields. Here, we present an efficient voltage-controlled strategy that simultaneously regulates water and ion diffusion by fine-tuning the external voltage applied to a high-conductivity Zr4-Ti3C2Tx nanochannel membrane, which demonstrates high structural stability in aqueous environments. Under positive voltage, ion permeation increased by a factor of 10.18, whereas negative voltage reduced it to 0.17 of its original value. Interestingly, water diffusion exhibited the opposite response, with negative voltage enhancing water transport due to the facilitated rotation motion of nanoconfined water with the increased interfacial hydrogen bonding. This distinct voltage-gated transport behavior provides a potential solution to the longstanding trade-off between permeation and selectivity in membrane separation. In desalination trials, applying negative voltage improved ion rejection from 72.09 % to 98.57 % and doubled water permeation. Additionally, in lithium concentration applications, our approach enabled simultaneous improvements in water permeation and Li+ rejection. Our findings open promising pathways for advancements in energy, resource, and environmental applications.