Progress on 3D-Printed Metal-Organic Frameworks with Hierarchical Structures

Metal-organic frameworks (MOFs) have attracted considerable attention in numerous applications due to their large surface areas, tunable pore size, and chemical versatility. However, the performance of most MOFs and their related derivatives in applications are still hindered due to their unoptimized form. Hierarchical nano-micromacropore MOF structure constructed by 3D printing has been shown to guide working species transportation routes, accelerates ion transportation, and increases the accessible area of MOF, thus leading to improved kinetics and enhanced application performances. Nevertheless, there is a lack of a review on 3D-printed MOFs and their applications that summarizes and promotes this field's progress. This review first introduces the progress of preparing and embedding MOF into structures via 1) MOF coating processes, 2) in situ growth of MOFs, and 3) using presynthesized MOFs to tune the nano- and microstructure of MOF. Subsequently, based on various 3D printing technologies, the principles behind various feedstock material preparation and their related printing processes are discussed with respect to the macrostructure. Thereafter, the advances and recent progress of various devices by 3D-printed MOFs are summarized with detailed analyses and discussion. Finally, an outlook in this promising field is proposed to provide a progression route for 3D-printed MOFs.