Liu Jieling,Yang Jiaji,An Shuyue,Wen Meiqi,Wang Xian,Gong Rongzhou,Nie Yan
Metal-organic framework (MOF) crystals have promising applications in a number of different fields, but the growth of MOF crystals with controllable morphology and high uniformity remains a major challenge. By taking the advantage of the synergistic effects of water molecules in the mixed solvent and polyvinylpyrrolidone (PVP) surfactants, this work demonstrates an approach for the preparation of NH 2 -MIL-88B(Fe) MOF crystals with both highly customizable size and aspect ratios and high uniformity. The effects of the concentration of water in the mixed solvent and the amount of PVP surfactants on the morphology and size of the MOF crystals were investigated. The morphology and crystalline properties were characterized by scanning electron microscopy and X-ray diffraction techniques. The data showed that through controlling the concentration of water in the solvent and the amount of the PVP surfactant, the size of the MOF crystals can be tuned rather widely, over 344–5.14 μm, while the aspect ratio of the crystals can be varied widely over 1.0–7.1. Possible mechanisms for such high tunability were discussed. As an example of potential applications, the complex permeability and permittivity of MOF-derived composites (25 wt%) were measured over a wide frequency range of 2–18 GHz. The parameters were then used to evaluate the potential for electromagnetic wave absorption. The results indicate that the composite with a thickness of only 1.2 mm exhibits a “− 10 dB” absorption bandwidth of 4.1 GHz and a minimum reflection of − 20 dB. Such bandwidth and reflection properties provide inspiration for future design of lightweight, broadband electromagnetic wave absorbers from the perspective of fine morphology control.
Ning Li,Chao Ma,Ziyue Wang,Dudu Li,Zhihua Qiao,Chongli Zhong
The MOF crystal-glass composites (CGC) membrane, comprising a MOF crystal and MOF glass matrix, represents a novel self-supported membrane that has been effectively applied in gas separation. Nevertheless, the typical MOF glass matrix requires a higher operating temperature (>400 °C), which constrains its combination with a multitude of MOF crystals characterized by high porosity and low decomposition. In this work, Zn-P-dmbIm (coordination polymer) was chosen as the glass matrix, and MIL-101 crystal with high porosity were integrated at an operating temperature of 190 °C. Furthermore, the intrinsic low porosity of a g Zn-P-dmbIm can be enhanced by the incorporation of higher porosity MIL-101, which possessed a high specific surface area (from ∼1.7 m 2 /g to 401 m 2 /g) and porosity (from ∼0.0014 cm³/g/nm to 0.5605 cm³/g/nm) of the CGC. The intimate combination of MIL-101 and a g Zn-P-dmbIm by in - situ melting to reduce the interfacial defects, which also provides a robust foundation for effective CO 2 /N 2 separation. In CO₂/N₂ (50/50, v/v) mixed gas conditions, the MIL-101/ a g Zn-P-dmbIm membrane demonstrated a impressively high CO₂ permeability of 18670 barrer and CO₂/N₂ selectivity of 61, exceeding the CO₂/N₂ upper bound. The variable pressure (1-12 bar) and long-term stability (120 h) of the CGC membrane exhibited enhancing separation stability. Hence, the self-supported MIL-101/ a g Zn-P-dmbIm membrane demonstrated effective CO₂/N₂ separation performance, which had the potential to significantly extend the scope of applications for MOF crystal-glass matrices.
危险品化学品经营许可证（带存储）