Membrane-based water treatment processes offer possibility to alleviate the water scarcity dilemma in energy-efficient and sustainable ways, this has been exemplified in filtration membranes assembled from two-dimensional (2D) materials for water desalination purposes. Most representatives however tend to swell or disintegrate in a hydrated state, making precise ionic or molecular sieving a tough challenge. Here we report that the chemically robust 2D carbon nitride can be activated using aluminum polycations as pillars to modulate the interlayer spacing of the conjugated framework, the noncovalent interaction concomitantly affords a well-interlinked lamellar structure, to be carefully distinguished from random stacking patterns in conventional carbon nitride membranes. The conformally packed membrane is characterized by adaptive subnanochannel and structure integrity to allow excellent swelling resistance, and breaks permeability-selectivity trade-off limit in forward osmosis due to progressively regulated transport passage, achieving high salt rejection (>99.5%) and water flux (6 L m⁻² h⁻¹), along with tunable permeation behavior that enables water gating in acidic and alkaline environments. These findings position carbon nitride a rising building block to functionally expand the 2D membrane library for applications in water desalination and purification scenarios.

基于膜的水处理工艺提供了以节能和可持续的方式缓解水资源短缺困境的可能性，这已经在由二维 (2D) 材料组装而成的用于海水淡化的过滤膜中得到了例证。然而，大多数代表在水合状态下往往会膨胀或分解，这使得精确的离子或分子筛分成为一项艰巨的挑战。在这里，我们报告化学坚固的二维氮化碳可以使用铝聚阳离子作为支柱来激活，以调节共轭框架的层间距，非共价相互作用同时提供了一个相互连接良好的层状结构，与传统的随机堆叠模式仔细区分氮化碳膜。⁻²  h ⁻¹ )，以及可调节的渗透行为，可在酸性和碱性环境中进行水浇注。这些发现将氮化碳定位为一个新兴的构建模块，可以在功能上扩展二维膜库，用于海水淡化和净化场景中的应用。