MICROCHIMICA ACTA
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2019
·Vol. 186
·期 6
·1-8
·
IF 5.479
Li Yufei,Zhang Huanhuan,Cai Xuan,Zhao Hongli,Magdassi Shlomo,Lan Minbo
Two kinds of carbon-based nanozymes were constructed from the same precursor of zeolitic imidazolate framework-8 (ZIF-8) for O 2 •− determination. Hollow carbon cubic nanomaterial (labelled as HCC) was obtained by chemically etching ZIF-8 with tannic acid and a subsequent calcination. A porous carbon cubic nanomaterial (labelled as PCC) was prepared by directly pyrolysis. Then HCC and PCC were immobilized on the surface of screen printed carbon electrodes (SPCE), fabricating HCC and PCC modified electrodes (denoted as HCC/SPCE and PCC/SPCE). HCC/SPCE, best operated at −0.5 V (vs. Ag/AgCl), has a sensitivity of 6.55 × 10 2 nA μM −1 cm −2 with a detection limit of 207 nM (at S/ N = 3) for O 2 •− sensing. And PCC/SPCE, best operated at −0.4 V (vs. Ag/AgCl), exhibited a superior performance for O 2 •− detection with a sensitivity of 1.14 × 10 3 nA μM −1 cm −2 and a low detection limit of 140 nM (at S/ N = 3). The two sensors possess excellent reproducibility and stability. They were used to sense O 2 •− released from HeLa cells.
Illustration of the synthesis of the hollow carbon cubic nanomaterial (HCC) and of the porous carbon cubic nanomaterial (PCC), and the scheme for detection of superoxide anions in HeLa cell.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2019
·
IF 4.784
Yating Wang,Xiu Dai,Yixing Zhan,Xiaoqing Ding,Ming Wang,Xinlong Wang
The zeolitic imidazole framework (ZIF-8) dotted chitosan (CS) nanocomposites (ZIF-8@CS) were fabricated via in-situ growth method. The morphology, structure and chemical state of ZIF-8@CS were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform IR spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorption behavior of ZIF-8@CS composites on Congo Red (CR) in aqueous solution was systematically investigated. The adsorption isotherm data showed that the adsorption of CR by ZIF-8@CS was single-layer adsorption, which was consistent with the Langmuir isotherm model. The maximum adsorption capacity of ZIF-8@CS was 922 mg/g. The kinetics parameters were in accord with pseudo-second-order equation, which implied that the adsorption rate was mainly controlled by the chemisorption mechanism. The removal of CR was attributed to the participation of hydrogen bonds , electrostatic interactions, π-π conjugation and zinc coordination effects.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Yifei Zhan,Jianwu Lan,Jiaojiao Shang,Lin Yang,Xinmei Guan,Wenxu Li,Siqi Chen,Ying Qi,Shaojian Lin
A ZIF-8/Ag/AgCl/TiO 2 modified PAN nanofibrous mat was successfully fabricated via stepwise in-situ growth method. The morphology and composition of the resultant ZIF-8/Ag/AgCl/TiO 2 modified PAN nanofibrous mat were confirmed by emission scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS) and electrochemical impedance spectroscopy (EIS), respectively. Next, methylene blue (MB) was employed as a contaminant to evaluate photocatalytic activity of prepared composite photocatalysts under visible light and natural sunlight irradiation. As expected, the ZIF-8/Ag/AgCl/TiO 2 decorated PAN nanofibrous mat exhibited high photocatalytic activity under both light sources, owing to the synergistic effect among ZIF-8, Ag/AgCl and TiO 2 . The degradation efficiency of the targeted PAN nanofibrous mat under visible light could reach to 98.02% within 120 min towards 20 mL of 50 mg/L MB aqueous solution. Most importantly, the fabricated ZIF-8/Ag/AgCl/TiO 2 modified PAN nanofibrous mat exhibited outstanding recyclability, the corresponding degradation efficiencies were up to 90.16% after five cycles and approximately 80% after ten cycles, respectively. Additionally, the resultant nanofibrous mat showed a long-term stability against acid and alkaline, and excellent antimicrobial performance against S. aureus and E. coli .
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SENSORS AND ACTUATORS B-CHEMICAL
·
2019
·
IF 6.393
Jiahao Wu,Chao Yu,Yujie Yu,Jun Chen,Chengli Zhang,Rufei Gao,Xinyi Mu,Yanqing Geng,Junlin He
A novel dual-mode aptasensor was fabricated for ultra-sensitive detection of microcystin-LR (MC-LR). The direct method was developed using chronoamperometry for quick detection. A glass carbon electrode (GCE) was first modified with MoS 2 -PtPd nanoparticles (NPs). MoS 2 -PtPd was used as a substrate for a higher loading of aptamers and to amplify the signal by catalytic activity toward H 2 O 2 . The aptamer was then assembled onto the modified electrode surface to work as a recognition probe to bind MC-LR. To increase the sensitivity of the aptasensor, we developed an indirect method for ultra-sensitive detection through synthesizing and utilizing novel zeolitic imidazolate framework (ZIF)-8-thionine (Thi)-Au as signal material for the first time. This signal material not only possessed the high conductivity of Au NPs, but also produced current signal from a redox reaction by Thi . The complementary strand of the aptamer was immobilized on the surface of ZIF-8-Thi-Au and their compounds hybridized with the aptamer on the MoS 2 -PtPd modified GCE. MC-LR would replace ZIF-8-Thi-Au compounds by competition binding with the aptamer. The electrical signal would decrease then and be detected by SWV. Under optimal conditions, the linear ranges of the indirect and direct methods were respectively 0.01–50 and 0.1–50 ng mL −1 . And LOD of the indirect and direct method were respectively 0.006 and 0.045 ng mL −1 (signal-to-noise ratio = 3). The aptasensor ensured the accuracy of the detection outcome through comparing the results of the two modes and provided a potentially reliable and ultra-sensitive detection method of MC-LR in water environments.
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ENERGY CONVERSION AND MANAGEMENT
·
2019
·
IF 7.181
Wenlei Xie,Fei Wan
In the current research, a porous solid base catalyst (ZIF-90-Gua) was prepared through covalent post-functionalization of zeolitic imidazolate framework ZIF-90 with organic guanidine via an imine condensation reaction. Various techniques such as XRD, SEM, FT-IR, XPS, EDX, TPD, Hammett indicator titration and nitrogen porosimetry measurements were employed to characterize the as-prepared solid catalyst. It was shown that the organic guanidine had been bound on the ZIF-90 frameworks by covalent imine linkages, and the primary crystalline structure of the imidazolium-based ZIF-90 was essentially maintained after the guanidine incorporation. This ZIF-90-Gua catalyst possessed an enhanced basicity, and interconnectivity, leading to highly catalytic activities. As a robust catalyst, the catalytic performances were evaluated in the heterogeneous transesterification of soybean oil with methanol for biodiesel production, and the maximum oil conversion to biodiesel of 95.4% was attained at reaction temperature of 65 °C, with a methanol/oil molar ratio of 15:1, catalyst dosage of 1 wt% (based on the oil mass) within reaction duration of 6 h. The solid catalyst could be easily recovered by filtration and reused for five times without significant decay of the catalytic activity, showing that it has great potential to be used as an efficient and durable catalyst for the clean production of biodiesel.
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Polymers
·
2018
·Vol. 10
·期 12
·1340
·
IF 2.935
Fang Zhang,Jing Dou,Hui Zhang
Two-dimensional metal–organic framework (MOF) nanosheets with molecular sieving properties and unique dimensional advantages are highly desired as polymer fillers for gas separation applications. Regarding polymer-supported MOF membranes, it is crucial to enhance the adhesion between the polymeric substrate and the MOF component and avoid MOF particle agglomeration. In this study, hydrophobic, embedded nanoporous nanosheets of a 2D zeolitic imidazolate framework synthesized using zinc salt and 2-methylimidazole (Hmim) aqueous solution (ZIF-L) were incorporated into a carboxymethyl cellulose (CMC) solution to form a steady mixed aqueous suspension through one-step solution blending. This prepared the composite membranes with a fine dispersion of ZIF-L nanosheets (up to loadings of 52.88 vol %) and good adhesion within the highly dense structural CMC matrix due to the strong interactions between ZIF-L and CMC, as confirmed by FTIR, Zeta potential, XPS, and SEM analysis. The potential advantages of CMC over classic polymer matrices used for gas separation mainly include: (a) Good interaction, (b) high dispersion of ZIF-L nanosheets, (c) the gas barrier nature of the CMC membrane, and (d) a facile water-based synthetic process. Based on the molecular sieving effect of ZIF-L and the gas barrier nature of the CMC matrix, gas permeation tests (H2, CO2, N2, CH4) of the mixed membrane showed a great improvement in gas selectivities compared with the CMC membrane and the reported pure ZIF membranes.Keywords:carboxymethyl cellulose;metal–organic framework nanosheets;interactions;gas permeability;gas selectivity
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CRYSTENGCOMM
·
2018
·Vol. 20
·期 34
·5056-5060
·
IF 3.304
Guangming Li,Xun Wang,Jilin Zhang
An environmentally friendly synthetic route for carbon dots/ZIF-8 fluorescent powders has been developed. It was found that the carbon dots can promote the growth of ZIF-8 crystals. The carbon dots/ZIF-8 fluorescent powders can be fabricated at a relatively low 2-methylimidazole/Zn2+ molar ratio (10 : 1) in aqueous solution at room temperature. Different morphologies and sizes of the carbon dots/ZIF-8 fluorescent powders are easily obtained by adjusting the 2-methylimidazole/Zn2+ molar ratio. The as-prepared carbon dots/ZIF-8 fluorescent powders can afford multi-colored imaging of latent fingerprints on different substrates and show great potential for latent fingerprint detection.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2018
·
IF 5.667
Tianjiao Qi,Xi Yang,Jie Sun
Based on the neck-controlled conduction model of chemiresistive gas sensors, construction of neck-controlled conduction networks in metal oxide films is an efficient method to improve their sensitivity. In this work, we develop a facile route to prepare the neck-connected ZnO (NC-ZnO) films with controllable diameters of the necked part by the sintering of core-shell zeolitic imidazolate framework-8 (ZIF-8)@ZnO films. In order to certify the enhancement of sensitivity by construction of neck-controlled conduction networks, their gas sensing properties towards ethanol are systematically investigated. The results demonstrate that the sensitivity of the optimal NC-ZnO film is dramatically improved, and the response value is about 6-times higher than that of ZnO film, reaching up to 124 ( I g /I a ) towards 50 ppm of ethanol. The results meet our expectation and are in conformity with the neck-controlled conduction model, which further indicates the developed approach in this work is expected to open up a new strategy for the preparation of neck-connected metal oxide films.
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JOURNAL OF SOLID STATE CHEMISTRY
·
2018
·
IF 2.179
Mengmeng Fan,Fangyuan Gai,Yu Cao,Zhenbo Zhao,Yuhui Ao,Yunling Liu,Qisheng Huo
This work demonstrated the design and synthesis of millimetre-scale hierarchical porous spheres based on ZIF-8 and CS (chitosan) by in situ assembly and post-thermal treatment technology. The ZIF-8/CS spheres have been synthesized according to the assembly method, which exhibited honeycomb internal structures and micropores of 0.77 nm. While the annealed ZIF-8/CS spheres exhibited obvious mesopores with a BET surface area of 626.85 m 2 g −1 and maintained the honeycomb internal structures, which were obtained by calcinations in the tube furnace under nitrogen protection at 500 °C for four hours. The annealed ZIF-8/CS spheres exhibited hierarchical porous with macropores, micropores and mesopores after annealing process. The SEM image and the XRD pattern of annealed ZIF-8/CS spheres suggested the maintenance of shape and crystal structure of ZIF-8, indicated that the annealed ZIF-8/CS spheres were stable and robust. Particularly, the CO 2 uptake of annealed ZIF-8/CS spheres with 500 °C is 0.99 mmol/g, which obvious higher than that of as-synthesized ZIF-8/CS spheres and samples annealed at 450 °C, 525 °C and 550 °C. The enhancement of CO 2 uptake may attribute to the carbonization of CS and the enlarge micropores of ZIF-8 after annealing process. This approach could induce a simple way for industrial structuring ZIF-8-based adsorbents with improved CO 2 uptake.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2015
·
IF 3.453
Hong Jiang,Qing Yan,Rizhi Chen,Weihong Xing
Pd@ZIF-8 nanoparticles with uniform size and morphology were prepared via an assembly method that enables the crystallization of ZIF-8 in methanol in the presence of polyvinylpyrrolidone (PVP)-modified Pd nanoparticles. The molar ratios of Pd/Zn 2+ and 2-methylimidazole (Hmim)/Zn 2+ are important parameters affecting the physical and catalytic properties of the Pd@ZIF-8. The catalytic activities of the hybrid catalysts were evaluated by the hydrogenation of p -nitrophenol to p -aminophenol. The results indicate that the increase of Pd loading and p -nitrophenol conversion can be tuned by adding more amounts of PVP-Pd colloid, but a suitable amount of PVP-Pd (Pd/Zn 2+ ≤ 0.012) is helpful to the control of particle size of Pd@ZIF-8 and encapsulation of the Pd nanoparticles within the ZIF-8 crystals. Pd@ZIF-8 catalysts prepared with excessive or equal molar of Hmim relative to Zn 2+ have similar morphology and uniform particle size, where the Pd nanoparticles are fully confined within the ZIF-8 crystals without aggregation. Furthermore, the Pd@ZIF-8 catalysts exhibit the better catalytic performance for the p -nitrophenol hydrogenation owing to the high loading of well-dispersed Pd nanoparticles with the decreased Hmim/Zn 2+ molar ratio. This work would aid the development of high-performance Pd@ZIF-8 catalysts.
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ACS Applied Materials & Interfaces
·
2017
·
IF 7.504
Cuiqing Wu,Qi Liu,Rongrong Chen,Jingyuan Liu,Hongsen Zhang,Rumin Li,Kazunobu Takahashi,Peili Liu,Jun Wang
Superhydrophobic coatings are highly promising for protecting material surfaces and for wide applications. In this study, superhydrophobic composites, comprising a rhombic-dodecahedral zeolitic imidazolate framework (ZIF-8@SiO2), have been manufactured onto AZ31 magnesium alloy via chemical etching and dip-coating methods to enhance stability and corrosion resistance. Herein, we report on a simple strategy to modify hydrophobic hexadecyltrimethoxysilan (HDTMS) on ZIF-8@SiO2 to significantly improve the property of repelling water. We show that various liquids can be stable on its surface and maintain a contact angle higher than 150°. The morphologies and chemical composition were characterized by means of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FI-IR). In addition, the anticorrosion and antiattrition properties of the film were assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization and HT, respectively. Such a coating shows promising potential as a material for large-scale fabrication.
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JOURNAL OF SEPARATION SCIENCE
·
2016
·Vol. 39
·期 18
·3647-3654
·
IF 2.741
Yan Xu,Jingjie Jin,Xianliang Li,Yide Han,Hao Meng,Junbiao Wu,Xia Zhang
Core–shell metal–organic framework materials have attracted considerable attention mainly due to their enhanced or new physicochemical properties compared with their single-component counterparts. In this work, a core–shell heterostructure of CoFe 2 O 4 -Zeolitic Imidazolate Framework-8 (ZIF-8@CoFe 2 O 4 ) is successfully fabricated and used as an solid-phase extraction adsorbent to efficiently extract Congo Red and Basic Red 2 dyes from contaminated aqueous solution. Vibrating sample magnetometry indicates that the saturated magnetization of ZIF-8@CoFe 2 O 4 is 3.3 emu/g, which is large enough for magnetic separation. The obtained hybrid magnetic metal-organic framework based material ZIF-8@CoFe 2 O 4 can remove the investigated dyes very fast within 1 min of the contact time. The adsorbent ZIF-8@CoFe 2 O 4 also shows a good reusability. After regeneration, the adsorbent can still exhibit high removal efficiency (∼97%) toward Congo Red for five cycles of desorption–adsorption. This work reveals the great potential of core–shell ZIF-8@CoFe 2 O 4 sorbents for the fast separation and preconcentration of organic pollutants in aqueous solution before high-performance liquid chromatography analysis.
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