An ultrathin and highly porous silica nanochannel membrane: toward highly efficient salinity energy conversion
An ultrathin and highly porous silica nanochannel membrane: toward highly efficient salinity energy conversion
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超薄且高度多孔的二氧化硅纳米通道膜：实现高效盐度能量转换
DOI：
10.1039/c8ta10848j
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发表时间：
2019-02-07
影响因子：
11.9
通讯作者：
Su, Bin
中科院分区：
文献类型：
--
作者：
Yan, Fei;Yao, Lina;Su, Bin
人工固态纳米通道能够调节单极离子在其受限空间中的传输，从而将储存在盐度梯度中的吉布斯自由能转化为电能。为了获得较高的转换效率，人们不可避免地需要具有高离子选择性和渗透性的纳米通道膜。在这项工作中，我们报道了一种超薄的二氧化硅等孔膜(SIM，厚度类似于90 nm)的盐度能量转换，它由直的、均匀的和紧密堆积的纳米通道(直径，2-3 nm；孔密度，类似于4×10(12)cm(-2)，相当于16.7%的孔隙率)组成。由于其独特的结构和带负电荷的表面，SIM显示出良好的阳离子选择性，同时保持了较高的离子通量，并能够在人工海水和河水混合时有效地利用渗透能量。通过有限元模拟，我们对存在盐度梯度的纳米通道内的离子分布以及通道长度对能量转换效率的影响进行了合理化。模拟结果表明，直径接近2.3 nm、长度接近100 nm的短纳米沟道具有良好的阳离子选择性。实验和理论结果都表明，SIM是一种很有潜力的盐度能量转换材料。
Artificial solid-state nanochannels are capable of regulating unipolar ion transport in their confined space and thus converting the Gibbs free energy stored in the salinity gradients to electricity. In order to achieve a large conversion efficiency, highly ion-selective and permeable nanochannel membranes are inevitably desired. In this work we report the salinity energy conversion using an ultrathin silica isoporous membrane (SIM, similar to 90 nm in thickness) that consists of straight, uniform and close packed nanochannels (diameter, 2-3 nm; pore density, similar to 4 x 10(12) cm(-2), corresponding to a porosity of 16.7%). Thanks to its unique structure and negatively charged surface, the SIM displayed excellent cation selectivity and meanwhile preserved a high ionic flux, and was capable of harnessing the osmotic energy efficiently upon mixing artificial seawater and river water. We rationalized the ion distribution inside the nanochannels in the presence of salinity gradients and the effect of the channel length on the energy conversion efficiency by finite element simulations. The simulated results suggest that short nanochannels with an ultrasmall dimeter of similar to 2.3 nm and a length of similar to 100 nm possess excellent cation selectivity. Both experimental and theoretical results suggest that the SIM is a highly potential material in salinity energy conversion.