New Approach of In Situ Dense Sphere Shaping of ZIF-7-III and ZIF-9-III in Water without Additive

The shaping of MOFs is a great challenge toward their use in plenty of applications. Herein we report the in situ spherical shaping of ZIF-7-III and ZIF-9-III triggered by the presence of water and a high excess of the benzimidazolate (bIm) ligand. Starting from different precursors (nitrates or sulfates) and after a mild heating hydrothermal synthesis, spheres of ZIF-7-III and ZIF-9-III were isolated after filtration. Their size varies between 10 and 30 μm by granulometry, and it remains quite homogeneous for the entire population. The spherical shape remains after calcination in order to prepare cathode materials of the LiCoO2 (LCO) type using ZIF-9-III as the precursor.