State Key Laboratory of Separation Membranes and Membrane Processes, Tianjin Polytechnic University , Tianjin 300387, China.
ACS Appl Mater Interfaces. 2017 Mar 29;9(12):11009-11015. doi: 10.1021/acsami.7b00174. Epub 2017 Mar 14.
Ion transport plays an important role in solar-to-electricity conversion, drug delivery, and a variety of biological processes. Carbon nanotube (CNT) is a promising material as an ion transporter in the applications of the mimicking of natural ion channels, desalination, and energy harvesting. Here, we demonstrate a unique, enhanced ion transport through a vertically aligned multiwall CNT membrane after the application of an electric potential across CNT membranes. Interestingly, electrowetting arising from the application of an electric potential is critical for the enhancement of overall ion transport rate through CNT membranes. The wettability of a liquid with high surface tension on the interior channel walls of CNTs increases during an electric potential treatment and promotes the formation of water channels in CNTs. The formation of water channels in CNTs induces an increase in overall ion diffusion through CNT membranes. This phenomenon is also related to a decrease in the charge transfer resistance of CNTs (R) after an electric potential is applied. Correspondingly, the enhanced ion flow rate gives rise to an enhancement in the capacitive performance of CNT based membranes. Our observations might have profound impact on the development of CNT based energy storage devices as well as artificial ion channels.
离子传输在太阳能转化为电能、药物输送以及各种生物过程中起着重要作用。碳纳米管（CNT）作为一种有前途的离子传输材料，在模拟天然离子通道、海水淡化和能量收集等应用中具有广阔的应用前景。在这里，我们展示了一种独特的增强离子传输现象，即在 CNT 膜上施加电势后，垂直排列的多壁 CNT 膜中的离子传输增强。有趣的是，由于施加电势引起的电润湿对于通过 CNT 膜的整体离子传输速率的增强至关重要。在电势处理过程中，具有高表面张力的液体在 CNT 内部通道壁上的润湿性增加，并促进 CNT 中形成水通道。CNT 中形成的水通道会导致 CNT 膜中整体离子扩散增加。这种现象也与施加电势后 CNT 的电荷转移电阻（R）降低有关。相应地，增强的离子流速会导致 CNT 基膜的电容性能增强。我们的观察结果可能对 CNT 基储能器件以及人工离子通道的发展产生深远的影响。
