Hollow metal–organic frameworks (MOFs) with only a shell may be used for efficient catalysis. In this work, a general sequential synthesis was employed to successfully create Hf-based hollow MOFs, such as UiO-66, MOF-808, and PCN-223. Etchants including monocarboxylic acids and H₂O are required to remove the interior of the MOFs to form hollow structures, while the different stability of the interior and surface of the MOFs partly resulting from surface epitaxy protection was responsible for the selective etching. With these insights, scale-up of hollow octahedral UiO-66 was realized. This work paves a way to rationally design hollow MOFs.

中文翻译：

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通过外延保护和选择性蚀刻制备中空金属有机骨架

只有壳的中空金属有机框架 (MOF) 可用于有效催化。在这项工作中，采用通用顺序合成成功地创建了基于 Hf 的空心 MOF，例如 UiO-66、MOF-808 和 PCN-223。需要包括一元羧酸和 H ₂ O在内的蚀刻剂来去除 MOF 的内部以形成中空结构，而部分由于表面外延保护导致的 MOF 内部和表面的不同稳定性是选择性蚀刻的原因。有了这些见解，实现了空心八面体 UiO-66 的放大。这项工作为合理设计空心 MOF 铺平了道路。