The preparation of high-quality highly oriented metal–organic framework (MOF) thin films is desirable for developing advanced functional devices. However, the pathways for controlling the oriented growth of MOFs are largely unknown, and determining their microcosmic evolution at the complex solid–liquid interface remains a challenge. Herein, we investigate the critical early growth stage of typical HKUST-1 on the COOH-functionalized Au substrate utilizing a combination of in situ surface-enhanced infrared spectroscopy, X-ray photoelectron spectroscopy, and photoinduced force microscopy. Detailed molecular level information indicates that it is not only the COOH-terminated SAM itself but also the distinct interfacial structures of the first metal coordinate layer and second ligand coordinate layer, which can be regulated in aprotic and protic solvents, that dominate the initial growth behavior of MOF and thus lead to the [111], [100], and polycrystal facet-oriented growth of HKUST-1. Moreover, the prepared HKUST-1 films exhibit a crystal facet-dependent catalytic rate in the chemical fixation of CO₂ into cyclic carbonate. Our observations provide a reasonable guide for designing MOF-based anisotropic functional equipment.

中文翻译：

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界面微环境调节的配位结构决定了金属-有机框架的刻面方向，以实现高效的 CO2 环加成反应


制备高质量高度取向的金属有机框架 （MOF） 薄膜是开发先进功能器件的理想选择。然而，控制 MOF 定向生长的途径在很大程度上是未知的，确定它们在复杂固液界面上的微观演变仍然是一个挑战。在此，我们利用原位表面增强红外光谱、X 射线光电子能谱和光诱导力显微镜的组合，研究了典型 HKUST-1 在 COOH 功能化 Au 衬底上的关键早期生长阶段。详细的分子水平信息表明，不仅是 COOH 封端的 SAM 本身，而且可以在非质子和质子溶剂中调节的第一金属配位层和第二配体配位层的不同界面结构，决定了 MOF 的初始生长行为，从而导致 HKUST-1 的 [111]、[100] 和多晶刻面导向生长。此外，制备的 HKUST-1 薄膜在 CO₂ 化学固定到环状碳酸酯中时表现出晶体刻面依赖性催化速率。我们的观察结果为设计基于 MOF 的各向异性功能设备提供了合理的指导。