Flow-induced voltage generation by driving imidazolium-based ionic liquids over a graphene nano-channel
Flow-induced voltage generation by driving imidazolium-based ionic liquids over a graphene nano-channel
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DOI：
10.1039/c8ta02629g
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发表时间：
2018-06
影响因子：
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通讯作者：
Yongji Guan;Qunfeng Shao;Wenqiong Chen;Jiao Zhang;Xiaoping Zhang;Youquan Deng
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文献类型：
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作者：
Yongji Guan;Qunfeng Shao;Wenqiong Chen;Jiao Zhang;Xiaoping Zhang;Youquan Deng
受一个有趣现象的启发，当液体中的盐含量流过细胞膜上高度选择性的离子通道时，生物系统具有产生显著生物电的固有技能，在这项研究中，本文首次利用分子动力学模拟技术，通过驱动纯块状室温离子液体（RTIL） 1-乙基-3-甲基咪唑四氟硼酸盐（[Emim][BF4]）流过由两个平行单层石墨烯片组成的石墨烯纳米通道，研究了流动感应电压。考虑到吸附层中阳离子和阴离子对石墨烯表面自由载流子的共同作用（相互作用分别为12.0和7.0 kJ mol−1 /正离子和石墨烯）以及库仑定律的特点，我们建立了一个先进的方程，可以在纳米尺度上有效准确地计算RTIL和石墨烯纳米通道系统的流致电压。由于石墨烯通道表面的自由载流子沿着纯体RTIL的运动方向被拖拽，该纳米级体系获得了2.3 μV的最大流致电压。随着流速的增加，流致电压趋于饱和，这种饱和可归因于外部驱动力与内部RTIL和石墨烯纳米通道产生的粘性阻力之间的平衡。进一步分析表明，当两个平行单层石墨烯之间的距离从1 ~ 5 nm增加到1 ~ 25 nm时，纳米通道的流动感应电压从1.9 ~ 2.1 μV逐渐趋于饱和，当单层石墨烯的面积从1 ~ 25 nm增加到2.3 ~ 2.1 μV时，流动感应电压逐渐减小。此外，还研究了系统温度（粘度）和平均流速对流致电压的影响。
Inspired by the interesting phenomenon that biological systems have the inherent skill to generate significant bioelectricity when the salt content in fluids flows over highly selective ion channels on cell membranes, in this study, the flow-induced voltage is investigated by driving the pure bulk room-temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF4]) flowing over a graphene nano-channel consisting of two parallel single-layered graphene sheets using molecular dynamics simulation for the first time. Considering the combined effect of cations and anions in the adsorbed layer on the free charge carriers of the graphene surfaces (the interactions are 12.0 and 7.0 kJ mol−1 per cation/anion and graphene, respectively) and the characteristic of Coulomb's law, we have developed an advanced equation that can effectively and accurately calculate the flow-induced voltage of RTIL and graphene nano-channel system on the nano-scale. A maximum flow-induced voltage of 2.3 μV is obtained from this nano-scaled system because the free charge carrier on the graphene channel surfaces is dragged along the pure bulk RTIL's direction of movement. A saturation of the flow-induced voltage with increased flow velocity is observed, and this saturation can be attributed to the balance between the external driving force and viscous resistance arising from the internal RTIL and graphene nano-channel. Further analysis shows that the flow-induced voltages gradually increase towards saturation from 1.9 to 2.1 μV or decrease from 2.3 to 2.1 μV when the distance between the two parallel single-layered graphene or the area of single-layered graphene of the nano-channel increases from 1 to 5 nm or from 1 to 25 nm2, respectively. Additionally, the influence of the system temperature (viscosity) and average flow velocity on the flow-induced voltage is investigated.