Salinity gradient (blue) energy has been identified as a promising power source and many technologies have been proposed for its recovery, one of which is nanopore power generators. The single-pore/channel membranes selectively transport ions to achieve efficient salinity gradient power generation. However, porous membranes fail due to concentration polarization. Here, we constructed a heterogeneous membrane by covering ion-selective hydrogel on a polyethylene terephthalate (PET) cylindrical nanochannel porous membrane for the first time to eliminate concentration polarization. The gel layer enhances the ion selectivity of cylindrical nanochannels, making heterogeneous membrane present the ion current rectification effect. The gel layer also avoids the negative impact of concentration polarization on the power generation of porous membranes. The results show that PET porous membrane can hardly generate electricity, but the power density of PET-hydrogel heterogeneous membrane can reach 1.92 W/m under 50 times salinity gradient, which is superior to commercial ion exchange membranes. Our work provides a strategy (ion-selective hydrogel covering) to eliminate concentration polarization of porous membranes, and shows the prospect of cylindrical nanochannels for salinity gradient power generation.

中文翻译：

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PET-水凝胶异质膜可消除盐度梯度发电的浓差极化

盐度梯度（蓝色）能量已被认为是一种有前途的能源，并且已经提出了许多技术用于其回收，其中之一是纳米孔发电机。单孔/通道膜选择性地传输离子以实现高效的盐度梯度发电。然而，多孔膜由于浓差极化而失效。在这里，我们首次通过在聚对苯二甲酸乙二醇酯（PET）圆柱形纳米通道多孔膜上覆盖离子选择性水凝胶来构建异质膜，以消除浓差极化。凝胶层增强了圆柱形纳米通道的离子选择性，使异质膜呈现出离子电流整流效应。凝胶层还避免了浓差极化对多孔膜发电的负面影响。结果表明，PET多孔膜几乎不能发电，但PET-水凝胶异质膜在50倍盐度梯度下的功率密度可达到1.92 W/m，优于商用离子交换膜。我们的工作提供了一种消除多孔膜浓差极化的策略（离子选择性水凝胶覆盖），并展示了圆柱形纳米通道用于盐度梯度发电的前景。