Hydrothermal synthesis of zeolitic imidazolate framework-67 (ZIF-67) nanocrystals

Thermally and chemically stable zeolitic imidazolate framework (ZIF) materials have attracted extensive application in gas adsorption and catalysis. Nano-sized ZIF-67 crystals (228 nm) were for the first time synthesized in aqueous solutions at room temperature. As-synthesized crystals were investigated by X-ray diffraction, field-emission scanning electron microscope, thermal gravimetric analysis, gas adsorption measurement. It was found that ZIF-67 nanocrystals were highly stable up to 350 °C and could be stable in boiling methanol at least for 5 days. Furthermore, the concentration of reagents plays an important role in controlling particle size, and diluting the synthesis solution can increase the particle size of final products.