Koseki Yuka, Okada Kenji, Hashimoto Shotaro, Hirouchi Shun, Fukatsu Arisa, Takahashi Masahide
Department of Materials Science, Graduate School of Engineering, Osaka Metropolitan University, Sakai, Osaka, 599-8531, Japan.
Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka, 599-8531, Japan.
Nanoscale. 2024 Jul 25;16(29):14101-14107. doi: 10.1039/d4nr01885k.
Fabricating high-quality thin films of metal-organic frameworks (MOFs) is important for integrating MOFs in various applications. Specifically, optical/electrical devices require MOF thin films that are crystallographically oriented, with closely packed crystals and smooth surfaces. Although the heteroepitaxial growth approach of MOFs on metal hydroxides has been demonstrated to control the orientation of the three crystallographic axes, the fabrication of MOF thin films with both three-dimensional crystallographic orientation and smooth surfaces remains a challenge. In this study, we report the fabrication of high-quality thin films of MOFs with closely packed MOF crystals, smooth surfaces, optical transparency, and crystal alignment by modulating the crystal growth of MOFs using the heteroepitaxial growth approach. High-quality thin films of Cu-paddlewheel-based pillar-layered MOFs are fabricated on oriented Cu(OH) thin films epitaxial growth using acetate ions as modulators to control the crystal morphology. Increasing the modulator concentration results in a uniform crystal shape with a relatively long one-dimensional pore direction and uniform heterogeneous nucleation over the entire film. The MOF thin films fabricated using the modulator exhibit high optical transparency. High-quality MOF thin films with dense and flat surfaces will pave the way for integrating MOFs into sophisticated optical and electrical devices.
制造高质量的金属有机框架（MOF）薄膜对于将MOF集成到各种应用中至关重要。具体而言，光学/电气设备需要具有晶体学取向、晶体紧密堆积且表面光滑的MOF薄膜。尽管已证明MOF在金属氢氧化物上的异质外延生长方法可控制三个晶体学轴的取向，但制备同时具有三维晶体学取向和光滑表面的MOF薄膜仍然是一项挑战。在本研究中，我们报告了通过使用异质外延生长方法调节MOF的晶体生长，制备出具有紧密堆积的MOF晶体、光滑表面、光学透明度和晶体排列的高质量MOF薄膜。基于铜桨轮的柱状层状MOF的高质量薄膜是在取向的Cu(OH)薄膜上通过外延生长制备的，使用醋酸根离子作为调节剂来控制晶体形态。增加调节剂浓度会导致晶体形状均匀，具有相对较长的一维孔方向，并在整个薄膜上实现均匀的异质成核。使用该调节剂制备的MOF薄膜具有高光学透明度。具有致密和平坦表面的高质量MOF薄膜将为将MOF集成到精密的光学和电气设备中铺平道路。
