Ordering of a Nanoconfined Water Network around Zinc IonsInduces High Proton Conductivity in Layered Titanate
Ordering of a Nanoconfined Water Network around Zinc IonsInduces High Proton Conductivity in Layered Titanate
复制标题
锌离子周围纳米承压水网络的有序化在层状钛酸盐中诱导高质子导电性
DOI：
10.1021/acs.chemmater.1c04421
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发表时间：
2022-05-10
影响因子：
8.6
通讯作者：
Dambournet, Damien
中科院分区：
文献类型：
--
作者：
Kang, Seongkoo;Reeves, Kyle G.;Dambournet, Damien
我们证明了Zn2+离子在无序层状钛酸锌结构层间空间的化学插入导致室温体积质子电导率从原始的8.11x10- 5sm -1急剧增加到钛酸锌的3.7x10- 2sm -1。由于这些化合物的晶体无序性质，我们结合不同的技术来建立结构-输运关系。对分布函数表明，化学插入Zn2+后，局部鳞片排列保持不变，为研究化学插入离子对层间空间输运性质和动力学的影响提供了一个合适的模型。宽带介电光谱（50 ~ 1010Hz）证实，Zn2+包合物通过H2O分子的自解离促进质子跳跃，产生高质子迁移率。利用Zn-K边缘扩展x射线吸收、精细结构和化学分析（EDX、TGA、1H NMR），表明Zn2+离子在层间空间内是稳定的byZnCl2（H2O）配合物。这种配合物引起氢键强度的增加，产生快速的质子运动。分子动力学模拟突出了水分子之间的质子转移，从结构中间层和结合到Zn2+离子。这些水分子之间不断增加的相互作用有利于质子在快速体质子电导率的起源上转移，这被认为是一个发生在远程顺序上的grotthuss型机制。这项工作提供了对离子-水相互作用如何介导离子传输的更好理解，并为可用于储能应用的离子导体的设计开辟了前景。
We demonstrated that the chemical intercalation of Zn2+ions within theinterlayer space of the structure of a disordered layered titanate results in a drasticincrease of the room-temperature bulk proton conductivity from 8.11x10-5Sm-1forthepristineto 3.7x10-2Sm-1forZn-titanate. Because of the crystallographic disorderednature of these compounds, we combined different techniques to establish the structural-transport relationships. The pair distribution function revealed that upon chemicalinsertion of Zn2+, the local lepidocrocite arrangement is maintained, providing a suitablemodel to investigate the effect of chemically intercalated ions on the transport propertiesand dynamics within the interlayer space. Broadband dielectric spectroscopy (50 to 1010Hz) enabled establishing that Zn2+inclusion promotes proton-hopping by self-dissociation of H2O molecules yielding high proton mobility. Using Zn-K edgeextended X-ray absorptionfine structure and chemical analyses (EDX, TGA,1H NMR), Zn2+ions were shown to be stabilized byZnCl2(H2O) complexes within the interlayer space. Such complexes induce an increase of the H-bonding strength as evidenced by1H NMR, yielding a fast proton motion. Molecular dynamics simulations highlighted proton transfer between water molecules fromthe structural interlayer and bonded to Zn2+ions. The increasing interactions between these water molecules favor proton transfer atthe origin of the fast bulk proton conductivity, which was assigned to a Grotthuss-type mechanism taking place at a long-range order.This work provides a better understanding of how ion-water interactions mediated ionic transport and opens perspectives into thedesign of ionic conductors that can be used in energy-storage applications.