OPTICAL MATERIALS
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2024
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IF 3.8
Yunqing Lu,Mengmeng Li,Yu Feng,Yuexin Xu,Yongqiang Zhou,Ji Xu,Jin Wang
Optical properties are the most significant properties of optical thin films, which determine its application in optical and photoelectric devices. Designable optical properties are the most challenging goals in optical material engineering. Recently, Metal-organic framework (MOF)-based optical thin films have attracted increasing attention due to their novel optical properties, especially their modular design, which allows fine-tuning of the relevant properties. In this work, a strategy for tuning the optical properties of MOF-based thin films is developed, which is realized by adjusting MOF crystal morphology. A commonly used MOF, ZIF-8 (zeolitic imidazolate framework-8), is selected as the research model. The morphology of ZIF-8 nanocrystal is adjusted using a surfactant/end-capping agent modulation method. The surfactant/end-capping agents are absorbed onto different crystal planes of ZIF-8, slowing the growth of the crystal planes and causing the formation of ZIF-8 crystals with different morphologies. Six different morphologies of ZIF-8 crystals are successfully synthesized in the presence of different amounts of CTAB and/or TRIS: nano-spherical, rhombohedral dodecahedron, nano-cubic, rough octahedron, flake-shaped and hexapod-like morphology. Then, the corresponding ZIF-8 thin films with different crystal morphologies are prepared via spin-coating. The optical properties of the thin films are investigated using UV–vis spectroscopy and ellipsometry in detail. The results indicate that the film with rough octahedron morphology has the best transmittance, reaching 93.35 % at 581 nm. As a key optical parameter of the film, its refractive index can be adjusted between 1.27 and 1.54. The success of tuning of the optical properties of MOF optical thin films by adjusting the crystal morphology will make it meet the different required optical properties in various optical and photoelectric devices.
研究领域:
材料科学
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光学工程
✓ 已验证
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 32
·13534-13541
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IF 3.288
Xin Gao,Qiang Ma,Zhengwei Jin,Pei Nian,Zheng Wang
Surfactant-stabilized oil–water emulsions are especially difficult pollutants to eliminate. Membrane technology has been extensively applied for oily water treatment. However, the immutable wettability limits its application for separating different types of emulsions. In this work, novel zeolitic imidazolate framework-8 (ZIF-8) film-coated stainless-steel meshes with switchable superlyophobicity were fabricated for all types of emulsion separations. The membranes exhibited outstanding superoleophobicity (161°) and superhydrophobicity (153°). By switching the superlyophobicity through a prewetting process, the membrane could selectively remove oil droplets in surfactant-stabilized oil-in-water emulsions via superoleophobicity and water droplets in surfactant-stabilized water-in-oil emulsions via superhydrophobicity. Upon further modification of the membrane with polyvinyl alcohol, high-flux emulsion separations were achieved. This work provides a foundation for the development of metal–organic framework (MOF) membranes for selective high-flux emulsion separations.
研究领域:
材料科学
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环境工程
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2022
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IF 5.518
Chenyang Wang,Jihui Wang,Wenbin Hu
ZnO@ZIF-8 films were prepared on Q235 steel surface through solvothermal reaction by pre-electrodepositing ZnO films and modified with stearic acid (SA). The surface morphology , elements content, crystal structure and chemical structure of films were studied by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The wettability of films was measured by water contact angle meter. The corrosion behavior of films was tested by Electrochemical tests. ZnO films show hexagonal nanotubular morphology, having the best compactness and corrosion resistance at deposition current density of 2.3 mA/cm 2 with the protection efficiency of 90.11%. After solvothermal reaction, ZIF-8 grains are formed and clad ZnO nanotubes , forming a contact film to prevent corrosive ions attacking steel efficiently. ZnO@ZIF-8 films have the best compactness and corrosion resistance at Zn 2+ concentration of 0.06 mol/L with the protection efficiency of 99.83%. But the corrosion resistance of ZnO@ZIF-8 film declines quickly for the water molecules can get inside the film and destroy the bond between ZIF-8 grains. Thus, SA was grafted to ZnO@ZIF-8 film to enhance its hydrophobicity . After SA modification, the protection efficiency reaches 99.99% and maintains at 95.29% after 14 days immersion in the solution of 3.5 wt.% NaCl .
研究领域:
材料科学
·
腐蚀与防护
✓ 已验证
产品关联
DOI
高影响因子
Analytical Methods
·
2015
·Vol. 7
·期 22
·9619-9628
·
IF 1.821
Dazhong Shen,Xiaolong Ma,Tingting Cai,Xilei Zhu,Xiaodong Xin,Qi Kang
In this work, the kinetic processes of zeolitic imidazolate framework-8 (ZIF-8) film growth and the adsorption of dichloromethane (DCM), trichloromethane (TCM) and carbon tetrachloride (CTC) on ZIF-8 film are monitored in real time using a quartz crystal microbalance sensor. It is shown that the growth kinetics of ZIF-8 film from a mixture of zinc nitrate and 2-methylimidazole consists of a rapid initial growth (0.22–1.1 μg cm−2 min−1) and later slow rearrangement stages. The time to obtain 50% of total equilibrium grown mass is in the range of 5.1–6.8 min. The mass deposited in the second, third and fourth cycles is 2.37, 3.36 and 4.08 times that in the first one (3.11 μg cm−2), respectively, and approaches a stable level after the fourth cycle. The as-prepared ZIF-8 film (0.70 μm) exhibits adsorption capacities of 568.3, 496.7 and 212.8 mg g−1 to DCM, TCM and CTC (20 °C), respectively. The initial adsorption rate of DCM is much higher than that of TCM and CTC. The difference in the adsorption behavior of the three chlorohydrocarbons is ascribed to the sieve effect of the pore apertures in ZIF-8 to the adsorbates. The adsorption kinetic data are in agreement with the pseudo-second-order model. For the adsorption in ZIF-8 film, the adsorption activation energies are 34.9 ± 5.6, 66.9 ± 5.5 and 49.1 ± 3.8 kJ mol−1; standard enthalpy changes of −63.2, −89.1 and −119 J mol−1, and standard entropy changes of −41.9, −45.3, and −50.1 kJ mol−1 K−1 have been evaluated for DCM, TCM and CTC respectively. The adsorption isotherms of DCM and TCM at 20 °C are fitted well by the Langmuir model while those of CTC and TCM at 60 °C follow the Freundlich model.
研究领域:
材料科学
·
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
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