Metal–organic framework (MOF) membranes have been extensively employed for a wide range of applications. Fabrication of high-quality MOF membranes is one of the prerequisites to ensure a good performance. Although various kinds of methods such as in situ growth, seeded secondary growth, interfacial synthesis, contra-diffusion synthesis methods, etc. have been developed for MOF membrane fabrication, their further practical application on a large scale is limited by poor control over the MOF membrane formation or complex fabrication procedures/devices. Developing simple methods that are capable of fabricating high-quality MOF membranes is still a big challenge and remains one of the vibrant topics in MOF membranes. Different from these methods, the self-confined conversion method features using insoluble solid matter instead of dissolved metal salt as metal precursors. During MOF growth, the formed MOF layer confines solid precursors from the organic ligand contributing to the formation of well-intergrown MOF membranes. Besides, by taking advantage of the interaction between guest components and solid precursors, different kinds of guest compounds can be feasibly encapsulated into the MOF membrane, further expanding their application field. Compared with other methods, the self-confined conversion method shows several advantages as follows: (i) good control over MOF nucleation and growth; (ii) high affinity between the MOF layer and the substrate; (iii) highly efficient encapsulation of guest components into the membrane; (iv) easy to scale up production. Solid precursors are the key issue in the self-confined conversion method. Among various kinds of solid precursors (e.g., zerovalent metal, metal oxide, layered double hydroxide, and metal hydroxide nanostrands), metal hydroxide nanostrands, a kind of unique metal hydroxide with a small diameter (<2.5 nm), a long length (a few micrometers), and a highly positively charged surface, are found to be an ideal solid precursor for MOF membrane fabrication and show several advantages such as a simple preparation procedure without the tedious solid hydrothermal and chemical vapor deposition operation, easy deposition on different substrates via suck filtration, high reactivity, and facile encapsulation of guest components into the MOF through electrostatic interaction. Therefore, this Account mainly summarizes our recent progress in the fabrication of MOF membranes through the self-confined conversion method using metal hydroxide nanostrands as the solid precursor. Meanwhile, the application of corresponding MOF membranes for gas separation, ion conduction and separation, electronic conduction, white light-emitting diode, derived carbon materials, and catalysis are discussed. Besides, challenges and opportunities for MOF membranes prepared by the self-confined conversion method are prospected to guide the future preparation of multifunctional MOF membranes.

中文翻译：

---

金属有机框架膜：金属氢氧化物纳米链的自限制转化

金属有机骨架（MOF）膜已广泛应用于各种领域。制造高质量的MOF膜是确保良好性能的先决条件之一。尽管人们已经开发出多种方法用于MOF膜的制备，如原位生长、晶种二次生长、界面合成、对向扩散合成方法等，但由于对MOF的控制较差，其进一步的大规模实际应用受到限制。膜形成或复杂的制造程序/设备。开发能够制造高质量 MOF 膜的简单方法仍然是一个巨大的挑战，并且仍然是 MOF 膜领域充满活力的主题之一。与这些方法不同，自封闭转化法的特点是使用不溶性固体物质代替溶解的金属盐作为金属前驱体。在 MOF 生长过程中，形成的 MOF 层限制了来自有机配体的固体前体，有助于形成良好共生的 MOF 膜。此外，利用客体组分与固体前驱体之间的相互作用，可以将不同种类的客体化合物封装到MOF膜中，进一步拓展了其应用领域。与其他方法相比，自限域转化方法具有以下几个优点：（i）对MOF成核和生长的良好控制；(ii) MOF层与基底之间的高亲和力；(iii) 将客体成分高效封装到膜中；(iv)易于扩大生产规模。固体前驱体是自封闭转化方法的关键问题。在各种固体前驱体（如零价金属、金属氧化物、层状双氢氧化物、金属氢氧化物纳米链等）中，金属氢氧化物纳米链是一种独特的金属氢氧化物，具有直径小（<2.5 nm）、长度长（a几微米）和高度带正电的表面，被发现是 MOF 膜制造的理想固体前体，并显示出多种优点，例如制备过程简单，无需繁琐的固体水热和化学气相沉积操作，通过吸滤、高反应性以及通过静电相互作用将客体成分轻松封装到 MOF 中。因此，本文主要总结了我们最近在以金属氢氧化物纳米链为固体前驱体，通过自限域转化法制备MOF膜方面取得的进展。同时，讨论了相应的MOF膜在气体分离、离子传导与分离、电子传导、白光发光二极管、衍生碳材料和催化等方面的应用。此外，还展望了自限域转化法制备MOF膜面临的挑战和机遇，以指导未来多功能MOF膜的制备。