A Simple Step toward Enhancing Hydrothermal Stability of ZIF-8

ZIF-8 is a flexible zeolitic imidazole-based metal-organic framework and has been extensively studied because of its high structural stability. However, ZIF-8 is hydrolyzed in water at higher temperature, resulting in degradation of its crystalline and porous structure. In order to prevent ZIF-8 from structural collapse due to the hydrolysis reaction of the metal-ligand bond and/or ligand substitution reaction, it is effective to shield the metal-ligand bond from the attack of water molecules. This work reports on the thermal and hydrothermal stability of mechanochemically synthesized ZIF-8 and presents an incredibly simple step to modify the outermost surface of ZIF-8, improving the hydrothermal stability. The partial carbonization resulting in the formation of a carbon-rich outermost layer endowed ZIF-8 with not only high hydrothermal stability but also a high adsorption rate on liquid phase adsorption.