Additively Manufacturing Metal−Organic Frameworks and Derivatives: Methods, Functional Objects, and Applications

Metal-organic frameworks (MOFs) are emerging porous crystalline materials that are composed of inorganic building units self-assembled with organic linkers. They have been intensively investigated because of their high porosity and designable functionality. However, one of the biggest drawbacks of MOF crystals is its large-scale application, primarily due to the rigid and brittle powder forms, as well as the low chemical stability and limited mechanical properties. Hence, the fabrication of MOF-based monolithic materials with easy recovery and tailorable shapes has become a fundamental challeng. To address, powdery MOFs need to be processed into structured monoliths with exceptional performance in well-defined and customizable forms. Additive manufacturing (AM), usually known as three-dimensional (3D) printing, has been considered as a potential strategy for manufacturing MOF-based structural and functional devices, where their properties can be regulated by the structure design to meet the practical application. Up to date, several 3D printing technologies such as fused deposition modeling, powder-based selective laser sintering, direct ink writing and digital light processing have been employed to engineer the customizable MOF components. Various 3D printed MOF structures and devices have been intensively investigated in various applications, such as 3D light-emitting objects with various shapes, 3D flow-through filters for capturing toxic gases, 3D scaffolds with drug delivery and bone regeneration, and 3D porous monolithic catalytic devices for water purification. Therefore, it is possible to construct MOF-based devices with desirable structures by combining 3D printing with MOF crystals to provide potentially industry-available commodities closely related with chemicals, environment, and energy.