Metal–organic frameworks (MOFs) are usually synthesized in powder form. For many practical applications, MOFs need to be shaped into monoliths that can be easily handled. However, conventional shaping methods, such as pelletization, often result in a decrease in functionality. Recently, MOF-containing monoliths have been made using direct ink writing (DIW; extrusion 3D printing), but to date, high additive loadings have been required. In this work, we demonstrate that colloidal gels containing only ethanol and Cu3(BTC)2 (BTC = 1,3,5-benzenetricarboxylate) (HKUST-1) nanoparticles can be used directly as an ink for the DIW of pure densely packed and self-standing MOF monoliths. The MOF gel shows ideal rheological properties for 3D extrusion-based printing, suggesting this method may be generalized to other MOF families that form gels. Importantly, the accessible porosity and surface area of the MOF is retained well after shaping. The 3D printed HKUST-1 monolith displays an exceptionally high BET surface area of 1134 m2/g, and a high mesopore volume. We demonstrate that for methane storage, a classical application of HKUST-1, the 3D printed monolith is comparable or superior to monoliths formed by other shaping methods.

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The ability of additive manufacturing to print mesh structure was exploited to fabricate highly efficient filtration meshes for oil/water separation applications. Through Direct Ink Writing (DIW) technique, pure cellulose acetate with a mesh architecture can be created easily, using cellulose acetate/ethyl acetate solution as the ink and simply drying off the solvent in ambient conditions. Besides conventional mesh structures, more complex structures can be fabricated in order to manipulate the pore size and hence tune the separation properties of the mesh. The superhydrophilic 3D-printed cellulose meshes are able to achieve a high separation efficiency of >95% as long as the average pore size is smaller than 280 μm. More importantly, the mesh that possesses an unconventional complex structure boasts a separation efficiency of ∼99% while maintaining a high water flux of ∼160 000 Lm 2− h −1 . The 3D-printed cellulose meshes are also able to separate oil substances of a wide range of viscosity, from highly viscous PDMS (∼97 cP) to nonviscous cyclohexane (∼1 cP) and are chemically resistant to extreme acidic and alkaline conditions. Moreover, the 3D-printed cellulose meshes also possess antioil-fouling/self-cleaning ability, which makes its surfaces resilient to contamination. In addition, the 3D-printed meshes do not suffer from surface inhomogeneity and interfacial adhesion issues as compared to the usual coated meshes. Such a robust yet practical system is highly applicable for highly efficient oil−water separation applications.

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A novel robust and self-standing 3D-printed pure copper framework (3DP-Cu) is developed as a Li host and current collector. 3D-printing allows microchannels to be deliberately incorporated, benefiting both mechanical and electrochemical performances.