Synthetic membranes with pores at the subnanometre scale are at the core of processes for separating solutes from water, such as water purification and desalination. While these membrane processes have achieved substantial industrial success, the capability of state-of-the-art membranes to selectively separate a single solute from a mixture of solutes is limited. Such high-precision separation would enable fit-for-purpose treatment, improving the sustainability of current water-treatment processes and opening doors for new applications of membrane technologies. Herein, we introduce the challenges of state-of-the-art membranes with subnanometre pores to achieve high selectivity between solutes. We then analyse experimental and theoretical literature to discuss the molecular-level mechanisms that contribute to energy barriers for solute transport through subnanometre pores. We conclude by providing principles and guidelines for designing next-generation single-species selective membranes that are inspired by ion-selective biological channels.

具有亚纳米级孔的合成膜是从水中分离溶质的过程的核心，例如水净化和脱盐。尽管这些膜工艺已经取得了巨大的工业成功，但现有技术的膜选择性地从溶质混合物中分离出单个溶质的能力受到限制。这种高精度的分离将使适合目的的处理成为可能，从而提高当前水处理工艺的可持续性，并为膜技术的新应用打开大门。在此，我们介绍了具有亚纳米孔的最新型膜对实现溶质之间高选择性的挑战。然后，我们将分析实验和理论文献，以讨论有助于溶质通过亚纳米孔传输的能垒的分子水平机制。最后，我们提供了设计和设计受离子选择生物通道启发的下一代单物种选择性膜的原则和指南。