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Selective Fluoride Transport in Subnanometer TiO2 Pores
ACS Nano ( IF 15.8 ) Pub Date : 2021-10-12 , DOI: 10.1021/acsnano.1c07210
Xuechen Zhou 1 , Mohammad Heiranian 1 , Meiqi Yang 1 , Razi Epsztein 2 , Kai Gong 3 , Claire E White 3 , Shu Hu 1 , Jae-Hong Kim 1 , Menachem Elimelech 1
Affiliation  

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 Å < d < 12 Å, with two distinct peaks at 5.5 and 6.5 Å), created by the hindered diffusion of ALD precursors (d = 7 Å), 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.

中文翻译:

亚纳米 TiO2 孔中的选择性氟化物传输

合成模拟离子选择性生物通道功能的纳米孔一直是推进精确离子-离子分离技术的一种具有挑战性但有前途的方法。受生物氟化物通道中促进氟化物 (F ) 渗透的启发,我们使用原子层沉积 (ALD) 技术设计了一种高度氟化物选择性的 TiO 2薄膜。制造的 TiO 2薄膜内的亚纳米空隙(4 Å < d < 12 Å,在 5.5 和 6.5 Å 处有两个不同的峰),由 ALD 前驱体的受阻扩散产生(d= 7 Å),与其他卤化钠相比,氟化钠的渗透速度快了八倍以上。我们表明,特定的Ti-F相互作用补偿F的能量损失- F的分配过程中的脱水-离子进入毛孔,并允许的F的intrapore积累-离子。同时,由于静电相互作用,F -离子在孔壁上的积累也增强了钠 (Na + ) 阳离子的传输。分子动力学模拟探测 TiO 2孔内的离子浓度和迁移率,进一步支持我们提出的选择性 F -传输和增强的 Na + 机制TiO 2薄膜中的渗透。总的来说,我们的工作为使用 ALD 技术设计离子选择性纳米孔提供了见解。
更新日期:2021-10-26
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