ACS Applied Materials & Interfaces
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2019
·
IF 8.456
Jialin Shi,Lina Zhang,Nannan Sun,Deng Hu,Qun Shen,Fang Mao,Qiang Gao,Wei Wei
Metal–organic frameworks (MOFs) are promising hosts for catalytic active sites due to their adjustable porosity and framework chemistry. Strategies to improve synergistic effects between the installed sites and the parent MOF are highly desired. Herein, a facile and rapid method for the preparation of xAg@ZIF-8 materials was reported. The materials were systematically characterized and used as catalysts for carboxylation of terminal alkynes via direct insertion of CO2 to the C(sp)–H bond (CTACO2). It was found that the integrity of the ZIF-8 structure could be retained upon Ag loading, but short-range crystalline ordering was modified. Two types Ag species could be installed, namely, highly dispersed Ag(I) in the backbone (AgHD) and aggregated Ag(0) nanoparticles on the outer surface (AgNP). The AgNP sites are highly effective for the activation of terminal alkynes due to its high accessibility, while the AgHD-modified ZIF-8 framework worked as a CO2 reservoir with enhanced affinity. Combination of these factors translated to high activity in the CTACO2 process, the measured turnover frequency and time yield are among the highest among most heterogeneous catalysts.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2019
·
IF 4.084
Feng Chen,Songlin Dong,Zhi Wang,Jiayou Xu,Rui Xu,Jixiao Wang
The incompatibility between nanofillers and polymer, caused by the agglomeration of nanoparticles and their weak interaction with each other, is still a challenge to develop mixed matrix composite membrane . Herein, we introduced the ZIF-8-TA nanoparticles synthesized by in situ hydrophilic modification into the hydrophilic poly(vinylamine) (PVAm) matrix to prepare composite membranes for H 2 purification. The dispersion of ZIF-8 in water was improved by tannic acid modification, and the compatibility between ZIF-8 particles and PVAm matrix was enhanced by chemical crosslinking between the quinone groups in oxidized tannic acid (TA) and the amino groups in PVAm. Moreover, the compatibility between hydrophobic polydimethylsiloxane (PDMS) gutter layer and hydrophilic separation layer was achieved by the adhesion of TA-Fe 3+ complex to the surface of PDMS layer during membrane preparation. The interlayer hydrophilic modification and the formation of separation layer were accomplished in one step, which simplified the preparation process. The experimental results indicated that when the TA addition used for modification was 0.5 g and the ZIF-8-TA 0.5 content in membrane was 12 wt%, the prepared membrane showed the best separation performance with the CO 2 permeance of 987 GPU and the CO 2 /H 2 selectivity of 31, under the feed gas pressure of 0.12 MPa.
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JOURNAL OF MEMBRANE SCIENCE
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2019
·
IF 7.015
Heng Mao,Hong-Gang Zhen,Ali Ahmad,Shen-Hui Li,Yue Liang,Jun-Fan Ding,Yao Wu,Lin-Zhi Li,Zhi-Ping Zhao
High separation performance and superior mechanical properties of the membranes are both of critical importance for membrane modules to achieve high efficiency and long-term stability. Herein, a series of mixed matrix membranes (MMMs) with brick-and-mortar architecture are prepared by incorporating two-dimensional zeolitic imidazolate framework-L (ZIF-L) nanosheets into polydimethylsiloxane (PDMS) matrix for separating alcohols (ethanol, n -propanol or n -butanol) from aqueous solution. The unique leaf-like morphology, flexible pore structure , and high hydrophobicity of ZIF-L nanosheets allow the straight and preferential permeation for alcohols; while the brick-and-mortar architecture renders the tortuous and intricate pathways for water, thus improving the membrane selectivity. Incorporating ZIF-L nanosheets endows the membranes with outstanding pervaporation performance, together with unusual and favorable increase in mechanical properties. More interestingly, the subtle interconnection of ZIF-L nanosheets creates the relatively continuous pathways for penetrants. Consequently, the resultant membrane displays a high separation factor (57.6) and a comparable permeation flux (402 g m −2 h −1 ) in separating 1.0 wt% n -butanol aqueous solution at 40 °C. Furthermore, the presence of ZIF-L nanosheets donates good thermal properties and promising long-term stability to the membranes. The findings of engineering brick-and-mortar architecture through two-dimensional porous fillers may provide new insights into designing high-performance MOF-based membranes for various applications.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2019
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IF 3.375
Yongcun Song,Nan Wang,Li-ye Yang,Yang−guang Wang,Di Yu,Xiao-kun Ouyang
Metal–organic frameworks (MOFs) have received special attention from scientists owing to their excellent adsorption performance. However, the difficulty in separating MOFs from adsorbed metals following use has limited their application. A zeolitic imidazole-based MOF with broad applicability for sorption of Pb(II) is examined. In this work, a novel adsorbent employing ZIF-8/calcium alginate microparticles was prepared using sodium alginate and ZIF-8. This adsorbent was characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. The performance of the ZIF-8@CA microparticles in adsorbing Pb(II) from a Pb(II) solution was investigated, and the impacts of the initial Pb(II) concentration, reaction time, pH, and reaction temperature on the reaction process were investigated. The results showed that ZIF-8@CA microparticles exhibited a maximum adsorption capacity of 1321.21 mg/g at pH 5 after 120 min, and the adsorption process was found to fit the Langmuir isotherm model (R2 = 0.9856) and the pseudo-second-order kinetic model (R2 = 0.9999). These results showed that the adsorption of Pb(II) was an endothermic process. The regeneration experiment with ZIF-8@CA revealed that the removal efficiency of Pb(II) was greater than 80% even after five cycles.
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APPLIED SURFACE SCIENCE
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2019
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IF 5.155
Meixia Wang,Jing Zhang,Xibin Yi,Xinfu Zhao,Benxue Liu,Xiaochan Liu
In this study, chitosan was used to prepare nitrogen-doped carbon aerogels (CAs) anchored by ZIF-8 derived porous carbon (ZIF-8-C) using a facile in-situ deposition method combined with subsequent carbonization. CAs possessing a 3D mesoporous structure with interlaced nanosheets can be used as the skeleton for growth of ZIF-8 derived microporous carbon. The coexistence of mesopores and micropores can not only create more channels for electrolyte ions accessing, but also can provide electrical-double-layer capacitance. The results of electrochemical performance revealed that the ZCCA composite electrode shows the large specific capacitance of 241.6 F/g at a current density of 0.5 A/g in 2.0 M KOH electrolyte and superior cycle performance (capacity retention of 90% after 5000 cycles). The improvement in the electrochemical properties is owed to its hierarchically porous structure, ultrahigh specific surface area and moderate nitrogen contents. The preparation method offers the smart design of CAs-supported MOF-derived material for high-performance energy storage applications.
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ANALYST
·
2018
·Vol. 143
·期 12
·2837-2843
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IF 3.864
Xueping Zhang,Qingqing Wang,Jing Li,Liang Huang,Dengbin Yu,Shaojun Dong
In this work, a novel electrochemical sensor for Cd(II) detection with differential pulse anodic stripping voltammetry (DPASV) is fabricated based on hollow ZnO@nitrogen-doped carbon (H-ZnO@NC) polyhedra, which are prepared from ZIF-8 via in situ tannic acid etching and a subsequent calcination process. The as-obtained H-ZnO@NC exhibits a polyhedral morphology with a well-defined hollow structure and a uniform distribution of elements C, N, O, and Zn in the shell. The unique structure of H-ZnO@NC can provide an enlarged surface area and abundant active sites. Moreover, ZnO has a strong affinity for heavy metals, which can enhance the adsorption capacity of H-ZnO@NC for Cd(II) in the accumulation step of stripping voltammetry, and thus improve the electrochemical sensing performances. As expected, the H-ZnO@NC-based sensor achieves a wide linear range of 0.3–300 μg L−1, a low detection limit of 0.1 μg L−1 (S/N = 3), and exhibits good selectivity as well as high stability and reproducibility. Moreover, the proposed electrochemical sensor can be applied for the determination of Cd(II) in real water samples, obtaining satisfactory results.
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CORROSION SCIENCE
·
2018
·
IF 4.862
Liangliang Xiong,Jianhua Liu,Mei Yu,Songmei Li
A two-dimensional nanocomposite, salicylaldehyde@ZIF-8/GO (SZG), was synthesized by anchoring the ZIF-8 nanoparticles containing the inhibitor salicylaldehyde (SA) on GO nanosheets for corrosion protection of AA2024 aluminum alloy. Its stimuli-responsive release of SA under acid and Al 3+ cations conditions was proved by UV–vis. Electrochemical impedance spectroscopy demonstrated that SZG nanocomposites prominently improved the protection properties of PVB coating by enhanced passive and active protection compared with the controlled samples. The enhanced passive protection derived from the two-dimensional structure of SZG, while inhibitor SA acted the active protection. Quantum chemical calculation clearly clarified the release and inhibition mechanisms of SA.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2019
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IF 4.182
Matteo Ciprian,Karla Hernandez Ruiz,Meruyert Kassymova,Tingting Wang,Serge Zhuiykov,Somboon Chaemchuen,Rong Tu,Francis Verpoort
3D metal N-doped carbon frameworks (M-NCFs) are produced from the direct pyrolysis of 2D zeolitic imidazolate frameworks (ZIF-L Zn and Co) in a reducing atmosphere. The effects of the thermal treatment were studied in order to achieve the desired catalyst. The results show that metal nanoparticles and N-doping species present in the carbon matrix have a direct influence on the catalytic performance. Zn/NCF-1000 displayed quantitative conversion and selectivity towards the chemical fixation of carbon dioxide through the cycloaddition with epoxides. Furthermore, the magnetic property of the newly synthesized Co/NCF-600 was used to demonstrate its superior stability and recyclability, retaining the same catalytic activity for more than 10 cycles.
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MICROCHEMICAL JOURNAL
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2015
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IF 2.746
Zhirong Zou,Shanling Wang,Jia Jia,Fujian Xu,Zhou Long,Xiandeng Hou
In this work, magnetic Fe 3 O 4 @ZIF-8 core-shell nanoparticles (MNPs) were employed for effective adsorption of inorganic arsenic for preconcentration , with adsorption mechanism thoroughly discussed. The adsorbed inorganic arsenic was easily separated by a magnet along with the MNPs from the sample matrix, with possible matrix interference eliminated. The MNPs were then completely dissolved in hydrochloric acid prior to the determination of inorganic arsenic by hydride generation-atomic fluorescence spectrometry. The Fe 3 O 4 @ZIF-8 MNPs were prepared with a facile step-by-step assembly method in aqueous solution at room temperature . Under the optimized conditions, the sensitivity for inorganic arsenic determination was significantly increased through preconcentration, with satisfactory analytical merits obtained.
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Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 20
·9937-9945
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IF 8.867
Huirong Chen,Kui Shen,Junying Chen,Xiaodong Chen,Yingwei Li
Semiconducting metal oxides have been considered as effective photocatalysts for the degradation of organic pollutants to decolorize contaminated water. However, the poor performance and difficulty in recycling greatly hinder their practical application. Herein, we designed and fabricated, for the first time, a novel ZnO@C–N–Co core–shell nanocomposite towards efficient and recyclable photocatalysis by directly pyrolyzing a hollow Zn/Co–ZIF matrix consisting of a ZIF-8 shell with some Co–ZIF nanoplates inside the hollow cavity. It was demonstrated that the ZIF-8-shell-derived ZnO nanoparticles could spontaneously agglomerate and move to the hollow cavity while the internal Co NPs transferred inversely to the ligand-derived N–C shell at suitable pyrolysis temperature, resulting in the unique ZnO@C–N–Co core–shell structure. This unique nanostructure possessed the following superior properties: (1) a core–shell structure may make the intermediate ZnO much more stable during the reaction; (2) a porous carbon shell can not only provide a high BET specific area and thus high adsorption capability for reactants, but can also inhibit the recombination of photogenerated electrons and holes; (3) the embedded Co NPs were able to provide richer electron traps that further suppress the recombination of electrons and holes. As exemplified for the degradation of methyl orange, the ZnO@C–N–Co showed a significantly improved performance and excellent recyclability due to the highly synergistic effects between the C–N–Co shell and the robust ZnO. This strategy for the synthesis of MOF-derived core–shell nanomaterials could offer prospects for developing highly efficient photocatalysts.
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JOURNAL OF NANOPARTICLE RESEARCH
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2017
·Vol. 19
·期 8
·1-11
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IF 2.02
Cheong Ling-Zhi,Wei Yayu,Wang Hongbin,Wang Zhiying,Su Xiurong,Shen Cai
Zeolitic imidazolate frameworks (ZIF) represent one of the metal organic frameworks (MOF) with high potential for enzyme immobilization due to their exceptional chemical and thermal stability, negligible cytotoxicity, and easy synthesis under mild biocompatible conditions. Amine-functionalized ZIF-8 (An-ZIF-8) are capable of forming multipoint attachment via hydrogen bonding with lipase which will immobilize and further enhance stabilization of lipase. In addition, increased hydrophilicity of An-ZIF-8 will increase partitioning of An-ZIF-8 immobilized lipase at the aqueous/organic interface which enable lipase to expose its active site and retain its catalytic activity at its highest. Present study reports the use of ZIF-8 and An-ZIF-8 nanoparticles as carrier for Burkholderia cepacia lipase (BCL), compares the ester hydrolysis and transesterification activities of immobilized lipase with those of free lipase, and evaluates the reusability and recovery rate of the immobilized lipase. An-ZIF-8 nanoparticles (average 130.42 ± 0.55 nm) were facilely synthesized via mixing ZIF-8 nanoparticles with ammonia hydroxide solution. Despite having similar characteristics of high crystallinity and forming cuboid-like particles, An-ZIF-8 demonstrated significantly ( P < 0.05) lower Brunauer-Emmett-Teller (BET) surface area and higher thermal stability than ZIF-8. BCL were successfully immobilized on ZIF-8 (BCL@ZIF-8) and An-ZIF-8 (BCL@An-ZIF-8) nanoparticles with an average lipase loading rate of ~ 8 mg/g MOF. The immobilized BCL demonstrated no significant differences in terms of esters hydrolysis and transesterification activities with those of free BCL. BCL@An-ZIF-8 demonstrated superior catalytic stability in comparison to BCL@ZIF-8 with retainment of more than 80% of its initial hydrolysis and transesterification activity for at least 10 repeated runs. In addition, more than 80% of the BCL@An-ZIF-8 can be easily recovered during each cycle of the reusability test through simple centrifugation.
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ACS Sustainable Chemistry & Engineering
·
2017
·
IF 5.951
Wenhui Li,Anfeng Zhang,Xiao Jiang,Chen Chen,Zhongmin Liu,Chunshan Song,Xinwen Guo
A Co-based zeolitic imidazolate framework, ZIF-67, has been utilized as a precursor to obtain Co-based porous carbon catalysts. The obtained catalysts display an outstanding catalytic performance toward the CO2 methanation at low temperature. The ZIF-67 crystal morphology can be controlled from cubic to rhombic dodecahedron, and the original particle sizes can be regulated from 150 nm to 1 μm in aqueous solution by cetyltrimethylammonium bromide (CTAB) surfactants. After carbonation in N2 flow, Co-based porous carbon catalysts kept the original ZIF-67 crystal morphology and particle size but differed in the micropore property; the 0.01 wt % CTAB content led to the maximum micropore volume 0.125 cm3/g. The Co nanoparticles inside the carbon matrix range between 7 and 20 nm, and they are separated by the graphite-like carbon avoiding the metal sintering effectively. Furthermore, the catalysts with 0.01% CTAB addition exhibited the highest CO2 conversion (52.5%) and CH4 selectivity (99.2%) under the 72000 mL g–1 h–1 GHSV (gas hourly space velocity) at 270 °C. Noticeably, the Co/PC catalysts performed higher activity and stability than the supported catalysts 20Co/AC. The versatile way offers good prospects for low temperature CO2 methanation and prevents metal sintering effectively.
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