Thin films of Co-MOF-74 and Ni-MOF-74 were synthesized on Au-coated quartz crystal microbalance substrates by a vapor-assisted conversion (VAC) method that precludes the need for activation via postsynthetic solvent exchange. All thin films were structurally characterized by powder X-ray diffraction, reflection–absorption infrared spectroscopy, and Raman spectroscopy. Scanning electron microscopy (SEM) images reveal that the Ni-MOF-74 films exists as a dense base layer with hemispherical protrusions on the surface. In contrast, the scanning electron microscopy images of the Co-MOF-74 thin films show a rough surface with spherical deposits. The thin film morphologies were different than the powders resulting from the bulk synthesis. Gravimetric vapor-phase adsorption measurements for xylene isomers and ethylbenzene within Co-MOF-74 and Ni-MOF-74 thin films were conducted, and the results were compared with those reported for the corresponding bulk powders. Despite different morphologies, the saturation capacities of Ni-MOF-74 and Co-MOF-74 thin films were found to be nearly equivalent to those reported for the bulk powders. The results demonstrate that the VAC method can produce MOF-74 thin films that retain the intrinsic properties that are observed in bulk powders.

中文翻译：

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MOF-74薄膜中二甲苯异构体和乙苯的气相吸附

Co-MOF-74 和 Ni-MOF-74 薄膜是通过气相辅助转换 (VAC) 方法在镀金的石英晶体微量天平基板上合成的，该方法无需通过合成后溶剂交换进行活化。通过粉末 X 射线衍射、反射-吸收红外光谱和拉曼光谱对所有薄膜进行结构表征。扫描电子显微镜 (SEM) 图像显示，Ni-MOF-74 薄膜以致密基层形式存在，表面具有半球形突起。相比之下，Co-MOF-74 薄膜的扫描电子显微镜图像显示具有球形沉积物的粗糙表面。薄膜形态不同于由本体合成产生的粉末。对 Co-MOF-74 和 Ni-MOF-74 薄膜内的二甲苯异构体和乙苯进行重量气相吸附测量，并将结果与​​相应散装粉末的结果进行比较。尽管形态不同，但发现 Ni-MOF-74 和 Co-MOF-74 薄膜的饱和容量几乎与报道的散装粉末的饱和容量相当。结果表明，VAC 方法可以生产 MOF-74 薄膜，该薄膜保留了在散装粉末中观察到的固有特性。