Shape engineering of metal–organic frameworks

Metal–organic frameworks (MOFs) are a class of porous materials prepared by the self-assembly of metal ions or clusters with organic ligands to form reticular structures. Studies of MOFs started by chemists who looked for materials with new porous structures and topologies. The unique characteristics of MOFs such as high surface areas, low densities, and structural tunability were soon realized and MOF materials have become the platform for applications in many scientific areas, ranging from gas separation to catalysis, magnetism, conductivity, sensing, drug delivery, electronics and others. Recently, the field has been directed towards large-scale synthesis of MOFs and their industrial applications. In terms of synthesis, MOFs are normally isolated as crystalline powders that are not industrially favorable due to their limitations in processing. Shaping MOFs into different forms while preserving or improving their properties offers several advantages as they can be easily processed, handled, and stored. Controlling the shape of MOFs in a systematic way can represent a major step forward to bringing them to the market, testing them at industrial scales and realizing their true potential. In this review, we firstly discuss the methods used to shape MOFs into granules, pellets, thin films, foams, gels, paper sheets and hollow structures, and then overview the importance of shaping towards potential industrial applications.