| 초록 |
Zeolitic imidazolate frameworks-8 (ZIF-8) are porous materials with chemical functions to separate, adsorb and desorb various gases. However, surface defects (e.g., grain boundaries or pinholes) degrade gas separation performance and emphasize developing growth protocols for highly uniform layers covering the support membrane. Here we demonstrate the synthesis of ZIF-8 layers by using ZnO-mediated ZIF-8 crystallites as the seeds for secondary growth on the c-Al2O3 a substrate. First, A densely packed ZnO seed layer was deposited on the substrate via RF sputtering. Then, the ZnO layers were solvothermally converted to ZIF-8 in 2-methylimidazole(2-mim) solution dissolved in methanol. Subsequently, the primary ZIF-8 crystallites were used as seeds for secondary growth using ZnCl2 solution. We propose the mechanism of the crystal growth process of ZIF-8 according to the conversion and secondary growth times based on XRD, XPS, SEM, and EDX analysis. Our results indicate that ZIF-8 crystals are strongly bound to the substrate, unlike the conventional method. These results propose an effective synthesis method of a full-covered ZIF-8 layers for enhanced gas separation performance. |
