Selective Fluoride Transport in Subnanometer TiO2 Pores
| Autor: | Xuechen Zhou, Meiqi Yang, Menachem Elimelech, Razi Epsztein, Mohammad Heiranian, Shu Hu, Jae-Hong Kim, Claire E. White, Kai Gong |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | ACS Nano. 15:16828-16838 |
| ISSN: | 1936-086X 1936-0851 |
| Popis: | Synthesizing nanopores which mimic the functionality of ion-selective biological channels has been a challenging yet promising approach to advance technologies for precise ion-ion separations. Inspired by the facilitated fluoride (F-) permeation in the biological fluoride channel, we designed a highly fluoride-selective TiO2 film using the atomic layer deposition (ALD) technique. The subnanometer voids within the fabricated TiO2 film (4 A < d < 12 A, with two distinct peaks at 5.5 and 6.5 A), created by the hindered diffusion of ALD precursors (d = 7 A), resulted in more than eight times faster permeation of sodium fluoride compared to other sodium halides. We show that the specific Ti-F interactions compensate for the energy penalty of F- dehydration during the partitioning of F- ions into the pore and allow for an intrapore accumulation of F- ions. Concomitantly, the accumulation of F- ions on the pore walls also enhances the transport of sodium (Na+) cations due to electrostatic interactions. Molecular dynamics simulations probing the ion concentration and mobility within the TiO2 pore further support our proposed mechanisms for the selective F- transport and enhanced Na+ permeation in the TiO2 film. Overall, our work provides insights toward the design of ion-selective nanopores using the ALD technique. |
| Databáze: | OpenAIRE |
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