日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

This article reviews the synthesis, compositing, and morphology control of metal–organic frameworks (MOFs) using spray-based processes. First, the synthesis of representative MOFs, including HKUST-1, UiO-66, and ZIF-8, is summarized from the viewpoint of droplet evaporation, nucleation, and crystal growth. In spray processes, rapid solvent evaporation strongly affects supersaturation, precursor condensation, and the formation of crystalline or amorphous intermediates, and these effects depend on the framework chemistry. In HKUST-1, evaporation rate, solvent properties, and precursor solution chemistry govern crystallinity and porosity. In UiO-66 systems, pre-formation of zirconium clusters is essential because the cluster formation time is often longer than the droplet drying time. In ZIF-8, incomplete coordination intermediates are first formed during drying and are subsequently converted into the final framework by solvent-induced recrystallization. The applicability of spray processes to other MOFs, multicomponent frameworks, and scale-up production is also outlined. The second part focuses on compositing and morphology control enabled by the use of droplets as reaction and assembly fields. Functional nanoparticles such as Fe₃O₄, TiO₂, Au/CeO₂, and Pd can be incorporated into MOFs in a one-step manner, leading to magnetic, photocatalytic, and catalytic functionalities. Spray processes also enable the fabrication of hierarchically porous MOFs with micro-, meso-, and macropores, the control of secondary particle morphology, and the preparation of thin films and free-standing composite films. These examples demonstrate that spray-based processing is not only a rapid synthesis route but also a versatile platform for structural design and practical shaping of MOF materials.