Jun Hu

East China University of Science and Technology, Shanghai, Shanghai Shi, China

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Publications (62)142.02 Total impact

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    ABSTRACT: Silver nanoparticle is an important catalyst for many chemical reactions and usually demands complex synthesis technology. In this work, a convenient and efficient plasma-assisted synthesis method was proposed to synthesize a new type of composite catalyst with Ag nanoparticles immobilized in 3D mesoporous cellular foams (MCFs) of silica. The plasma treatment under O2 atmosphere provided more activated silanol groups on the surface of MCF for the immobilization of Ag nanoparticles. The properties of immobilized Ag nanoparticles, such as smaller average size, higher loading, and better dispersion state greatly improved the reaction rate of the catalytic reduction of 4-nitrophenol (4-NP). Among them, with an average size of 6.0 nm and 2.6 wt% immobilized Ag nanoparticles, the catalyst MCF-100-Ag-0.01 showed the best catalytic activity for the reduction of 4-NP, that the apparent reduction rate constant was as large as 2.66 × 10−2 s−1, and the turnover frequency coefficient was as extremely high as 8.97 × 1018 molecules g−1 s−1. The MCF-n-Ag-m composites could be expected as attractive catalysts for many other catalytic reactions. More importantly, this plasma-assisted synthesis approach could be a convenient way for the synthesis of highly active catalysts by immobilizing various types of metal nanoparticles in porous materials.
    Microporous and Mesoporous Materials 05/2015; 207. DOI:10.1016/j.micromeso.2015.01.025 · 3.21 Impact Factor
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    ABSTRACT: A novel method of an in-situ interfacial growth of nanoparticles induced by the Pickering emulsion was proposed for the fabrication of hollow composites. With the interfacial growth of ZIF-8 nanoparticles at n-octanol/water interface of the Pickering emulsion stabilized by graphene oxide (GO), the hollow ZIF-8/GO composite was obtained.
    RSC Advances 03/2015; DOI:10.1039/C5RA02779A · 3.71 Impact Factor
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    ABSTRACT: For the real industrial process of CO2 capture, it is still a great challenge for adsorbents to exhibit excellent CO2 adsorption capacity in the presence of water. By combining a pre-seeding process and a two-step temperature controlling crystallization, zeolitic imidazolate framework (ZIF-8) shell is introduced on the commercial zeolite adsorbent (5A) core to produce a series of 5A@ZIF-8 composites with an enhanced surface hydrophobicity. Each 5A@ZIF-8 composite exhibits a dynamic hydrophobic hindrance effect for the separation CO2 from the simulated humid flue gas (15% CO2 and 90% humidity at 298 K). Among them, the CO2 adsorption capacity and the CO2/H2O selectivity of 5A@ZIF-8(I) can be as high as 2.67 mmol g-1 and 6.61 at the optimized adsorption time of 10 min. More importantly, over 10 adsorption-desorption cycles, there is almost no degradation of adsorption performance. Therefore, the novel strategy of utilizing the dynamic hydrophobic hindrance effect through a core-shell structure would be a good solution for improving the CO2 separation performance in practical applications.
    03/2015; DOI:10.1039/C4TA06645F
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    ABSTRACT: In through-wall indication of a moving human target in enclosed structures, a shadow effect because of the human target blocking parts from illumination on the back wall will emerge, referred to as a “ghost” in indication results. The shadow ghost moves as the human target does, which makes causal change detection (CD) invalid to separate them. To mitigate the shadow ghost, we analyze its differences from the moving human target. Based on the difference that the illumination is only blocked in partial channels of the multiple-input–multiple-output (MIMO) array while target echoes exist in most channels and the fact that shadow ghosts overlap more between successive indication results than the imaged targets as a result of their larger size, we proposed a mitigation method including a coherence factor and noncausal CD processing. Through-wall experiments via a MIMO through-wall imaging radar validate the proposed method.
    IEEE Geoscience and Remote Sensing Letters 03/2015; 12(3):453-457. DOI:10.1109/LGRS.2014.2345777 · 1.81 Impact Factor
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    ABSTRACT: Plasma technology, an efficient and important approach for the surface modification, has been widely adopted for the treatment on the exposed surface of planar substrates. In this work, plasma treatment was demonstrated to be an effective way for the internal surface modification in one-dimensional channels of mesoporous SBA-15 particles, which is not a general planar substrate. Upon the plasma treatment in O-2 atmosphere, the silanol groups on the surface of channels were intensively activated, as a result, large amounts of amine groups (2.56 mmol (APTS)/g(sample)) can be effectively grafted within a very short time (2 h). The highly dispersed amine groups inside the channels can be facilely revealed by the location of in-situ coordinated Ag nanoparticles. Moreover, the amine-modified SBA-15 via the plasma treatment exhibited a better CO2 adsorption capacity (1.26 mmol/g) comparing with the traditional amine-modified SBA-15. Thus, our new approach may pave the way towards the rational modification and effective activation for porous materials, which would be meaningful for functionalization applications.
    Microporous and Mesoporous Materials 01/2015; 202:16–21. DOI:10.1016/j.micromeso.2014.09.020 · 3.21 Impact Factor
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    ABSTRACT: Hierarchical porous metal organic framework (MOF) composites are highly demanded because they can keep the high activity and good transport property simultaneously. A novel method of ionic liquidassisted growth of Cu-3(BTC)(2) on graphene oxide (GO) sheets was proposed and applied to improve both CO2 adsorption capacity and adsorption rate. Three ionic liquids (ILs) of triethylene tetramine acetate (TETA-Ac), triethylene tetramine tetrafluoroborate (TETA-BF4) and 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) were used to investigate the effects of cations and anions of ILs on the structure of GO-IL/MOF composite. With amine or imidazole cations adsorbed at the surface of GO and the contrary anions closely attached, GO-ILs can provide a lot of active sites for the absorption of Cu2+ cations through the coordination. Just like a bridge, ILs assisted the initial growth of the first seed layer of Cu-3(BTC)(2) on the surface of GO. Among various GO-IL/MOP composites, GO-TAc/MOF-60 sample showed a superimposed structure, which lead to more accessible adsorption activity sites and shorten the transfer distance. Also, the GO sheets in GO-IL/MOF provide channels for faster transfer. It showed a high CO2 adsorption capability of 5.62 mmol/g at 25 degrees C and 100 kPa, and a high CO2 kinetic separation performance as well. More importantly, the composite presented a quite good cyclic adsorption/desorption stability. The relations between the specific structures of the composites and the CO2 adsorption behaviors were tentatively demonstrated to reveal a convenient way for designing and fabricating hierarchical MOF composites.
    Microporous and Mesoporous Materials 12/2014; 200:159–164. DOI:10.1016/j.micromeso.2014.08.012 · 3.21 Impact Factor
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    ABSTRACT: Thiazolothiazole-linked porous organic polymers have been synthesized from a facile catalyst-free condensation reaction between aldehydes and dithiooxamide under solvothermal condition. The resultant porous frameworks exhibit a highly selective uptake of CO2 over N2 at ambient conditions.
    Chemical Communications 10/2014; 50(95). DOI:10.1039/C4CC07255C · 6.72 Impact Factor
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    ABSTRACT: TiO2 microspheres with various amounts of carbon-residue, such as core/shell C@TiO2, hollow neat H-TiO2, and hollow C/TiO2 composites have been obtained via one-pot hydrothermal process. With a thin shell of TiO2 nanoparticles and carbon-residues, the capacity of hollow C/TiO2 composite maintains at 143.3 mAh · g− 1 at 0.5 C (83.5 mA · g− 1) after 100 cycles.
    Chinese Journal of Chemical Engineering 10/2014; DOI:10.1016/j.cjche.2014.09.005 · 0.87 Impact Factor
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    ABSTRACT: Mixed micelle template approach is one of the most promising synthesis methods for hierarchical porous materials. Although considerable research efforts have been made to explore the formation mechanism, an explicit theoretical guidance for appropriately choosing templates is still not available. We found that the phase separation occurring in the mixed micelles would be the key point for the synthesis of hierarchical porous materials. Herein, the pseudo-phase separation theory for the critical micelle concentration (cmc) combining with the Flory-Huggins model for the chain molecular mixture were employed to investigate the properties of mixed surfactant aqueous solution. The cmc values of mixed surfactant solutions were experimentally determined to calculate the Flory-Huggins interaction parameter between two surfactants, χ. When χ is larger than the critical value,χc, the phase separation would occur within the micellar phase, resulting in two types of mixed micelles with different surfactant compositions, and hence different sizes, which could be used as the dual-template to induce bimodal pores with different pore sizes. Therefore, the Flory-Huggins model could be a theoretical basis to judge whether the mixed surfactants were the suitable templates for inducing hierarchical porous materials. We chose cetyltrimethylammonium bromide (CTAB) and n-octylamine (OA) as a testing system. The phase separation behavior of the mixed solutions, as well as the successful synthesis of hierarchical porous materials by this dual-template indicated the feasibility of preparing hierarchical porous materials based on the concept of phase separation of the mixed micelles.
    Langmuir 09/2014; 30(38). DOI:10.1021/la501648j · 4.38 Impact Factor
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    ABSTRACT: The world becomes more stringent on keep lowering the sulfur concentrations in fuels. To fulfill this expectation, a new type of magnetic desulfurization adsorbent of Fe3O4@PAA@MOF-199 was designed and fabricated by a facile two-step assembly approach, in which PAA inventively acted like a bridge to incorporate different amounts of the magnetite Fe3O4 into MOF-199 crystal matrix. Fe3O4@PAA@MOF-199s were demonstrated to be efficient adsorbents for the removal of S-compounds of thiophene, benzothiophene (BT) and dibenzothiophene (DBT) from a model fuel, and the sulfur saturated adsorption capacity followed the order of DBT > BT > thiophene. The magnetization of Fe3O4@PAA@MOF-199s insured the adsorbents a good performance in magnetic separation. The relative high adsorption capacity, the separation efficiency, as well as the stable recyclability indicated that magnetic Fe3O4@PAA@MOF-199 would be a promising adsorbent in adsorptive desulfurization.
    RSC Advances 08/2014; DOI:10.1039/C4RA06515H · 3.71 Impact Factor
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    ABSTRACT: A porous triazine and carbazole bifunctionalized task-specific polymer has been synthesized via a facile Friedel-Crafts reaction. The resultant porous framework exhibits excellent CO2 uptake (18.0 wt%, 273 K and 1 bar) and good adsorption selectivity for CO2 over N2.
    Chemical Communications 05/2014; DOI:10.1039/c4cc01588f · 6.72 Impact Factor
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    ABSTRACT: Through-wall indication of human targets is highly desired in many applications. Generally, human targets behind wall are noncooperative, and rare prior knowledge about the circumstance behind wall could be available. Thus, it requires the ability to indicate human targets with different motions from clutters. To investigate this problem, we first examine the conventional time-domain indication methods, and find that their performances are controlled by the historical pulse number adopted to estimate background, which corresponds to the tap-length from the angle of filter. Then, based on an intermittent mode of human target echoes, we define the optimum tap-length as the shortest tap-length that makes the filter output signal-to-clutter-and-noise ratio reach maximum and develop an adaptive indication method with a gradient tap-length control scheme to search the optimum tap-length. Finally, through-wall experiments with an impulse through-wall radar demonstrate that the proposed method can obtain a good adaptive indication performance on human target with different motions.
    IEEE Geoscience and Remote Sensing Letters 04/2014; 11(5). DOI:10.1109/LGRS.2013.2281813 · 1.81 Impact Factor
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    ABSTRACT: A fully atomistic simulation study is reported to provide mechanistic insight into the superior performance experimentally observed for a polymer membrane (Carta et al., Science, 2013, 339, 303-307). The membrane namely PIM-EA-TB is produced by a shape-persistent ladder polymer of intrinsic microporosity (PIM) with rigid bridged bicyclic ethanoanthracene (EA) and Tröger's base (TB). The simulation reveals that PIM-EA-TB possesses a larger surface area, a higher fraction free volume and a narrower distribution of torsional angles compared to PIM-SBI-TB, which consists of less rigid spirobisindane (SBI). The predicted surface areas of PIM-EA-TB and PIM-SBI-TB are 1168 and 746 m(2) g(-1), close to experimental values of 1120 and 745 m(2) g(-1), respectively. For five gases (CO2, CH4, O2, N2 and H2), the solubility and diffusion coefficients from simulation match well with experimental data, except for H2. The solubility coefficients decrease in the order of CO2 > CH4 > O2 > N2 > H2, while the diffusion coefficients increase following CH4 < CO2 < N2 < O2 < H2. In terms of the separation for CO2/N2, CO2/CH4 and O2/N2 gas pairs, PIM-EA-TB exhibits higher permselectivities than PIM-SBI-TA, in good agreement with experiment. From a microscopic perspective, this simulation study elucidates that the presence of bridged bicyclic units in PIM-EA-TB enhances the rigidity of polymer chains as well as the capability of gas permeation and separation, and the bottom-up insight could facilitate the rational design of new high-performance membranes.
    Physical Chemistry Chemical Physics 02/2014; 16(13). DOI:10.1039/c3cp55498h · 4.20 Impact Factor
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    ABSTRACT: Abstract Context: Release of two drugs safely and independently should be necessary in medical or reaction engineering fields to overcome many complex problems such as multi-drug resistance in treatment of disease. Objectives: Core-shell structural microparticles that can load/release two drugs simultaneously are designed and prepared. Materials: The microparticles are composed of mesoporous silica core and hyaluronate (HA)/poly (N-isopropylacrylamide) hybrid gel shell. Methods: The synthesis processes are monitored by powder x-ray diffraction and Fourier transform infrared spectroscopy. The properties of microparticles are characterized by nuclear magnetic resonance, dynamic light scattering and transmission electron microscope methods. Two kinds of drugs are loaded into the mesoporous-core and gel-shell, respectively, and then released under various conditions. Results: The microparticles show uniform spherical shapes with core-shell structures. When temperature is higher than the lower critical solution temperature, the microparticles shrink abruptly and assemble. The drug release rates have been found to depend on the concentration of the microparticle suspensions and pH of the release medium. Discussion: The swellability of the microparticles are controlled by the HA size and gel crosslink density; and the main effect factors on drug releasing behavior are the drug properties and drug diffusion ability. Conclusion: The experimental results confirmed different drugs could be safely loaded into the core-shell structural microparticles and released independently, which might be potential carriers for drugs or catalysts. These microparticles would be expected to make sense for applying in medical or reaction engineering fields.
    Drug Delivery 11/2013; DOI:10.3109/10717544.2013.859768 · 2.20 Impact Factor
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    ABSTRACT: Composing of both zeolite and mesoporous structures, micro/mesoporous composites exhibit promising CO2 capture capabilities. In this work, a full-atomic mimetic 5A-MCM-41 structure with bimodal pores has been constructed, in which the microporous structure of 5A zeolite is constructed and optimized based on zeolite A with Ca and Na cations introduced; whereas the mesoporous MCM-41 structure is produced by caving the cylindrical pores in the obtained 5A zeolite matrix. CO2 adsorption on 5A-MCM-41 has been simulated by the grand canonical Monte Carlo (GCMC). The simulation results demonstrated that CO2 is preferentially adsorbed in micropores, and the CO2 adsorption capacity and its isosteric heat on 5A-MCM-41 are much larger than those of N-2. The CO2 selectivity of 5A-MCM-41 results from the electrostatic interaction of the quadrupole CO2 molecule with Ca2+ cations of the zeolite. Furthermore, the hierarchical micro/mesoporous composites are synthesized to verify the simulated predictions. By the hydrothermal reaction using 5A zeolite "seeds" as the silicon source and hexadecyl trimethylammonium bromide (CTAB) as the mesoporous template, 5A-MCM-41 composites are obtained, the characteristic results show that typical 5A microporous structure is remained and disordered mesoporous networks are produced in the composites. Moreover, the CO2 adsorption capacity of the 5A-MCM-41 composites can reach as high as 4.08 mmol/g at 100 kPa and 298 K. These observations have been strongly supported that micro/mesoporous composites with metal ions located would be promising adsorbents for CO2 separation. (c) 2013 Elsevier Masson SAS. All rights reserved.
    Solid State Sciences 10/2013; 24:107-114. DOI:10.1016/j.solidstatesciences.2013.07.008 · 1.68 Impact Factor
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    ABSTRACT: Nano-crystalline Li4Ti5O12 with an average size of 18 nm was in situ grown on graphene sheets using ionic liquid of C12H23ClN2 [Omirn]Cl as the exfoliated agent. Such unique nanostructure provides a high electrode/electrolyte area for the electron transport and the nanosized Li4Ti5O12 leads to a short path for the lithium ion transfer. When used as an anode material for lithium-ion battery, the Li4Ti5O12/graphene nanostructure exhibits excellent reversibility (159 mAh g(-1) at 0.5 C after 100 cycles) and high-rate performance (162 mAhg(-1) at 0.2 C, 148.5 mAhg(-1) at 20 C). Crown Copyright
    Electrochimica Acta 10/2013; 109:389-394. DOI:10.1016/j.electacta.2013.07.059 · 4.09 Impact Factor
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    ABSTRACT: A concentric multilayer vesicle with mesoporous channels in each layer was synthesized and used as a drug carrier. The average size of the vesicles was about 100-300 nm, with the cavities of an average distance of about 7 nm between every two layers, and the mesoporous channels of an average diameter of 3.4nm in each layer. Ibuprofen was selected as the drug model to investigate the vesicle's loading and releasing performance. The vesicle showed a fast loading with the ibuprofen capacity (weight ratio of ibuprofen to material) of 30% within 2 h, and a slow controllable release during about 15 h. The Weibull model can be successfully used to describe the release performance. The analysis results demonstrated that fast loading and slow release of the vesicle were mainly attributed to its mesoporous multilayer structure.
    Colloids and Surfaces A Physicochemical and Engineering Aspects 09/2013; 436:1021-1026. DOI:10.1016/j.colsurfa.2013.08.026 · 2.35 Impact Factor
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    ABSTRACT: A 3D Tröger’s-base-derived microporous organic polymer with a high surface area and good thermal stability was facilely synthesized from a one-pot metal-free polymerization reaction between dimethoxymethane and triaminotriptycene. The obtained material displays excellent CO2 uptake abilities as well as good adsorption selectivity for CO2 over N2. The CO2 storage can reach up to 4.05 mmol g–1 (17.8 wt %) and 2.57 mmol g–1 (11.3 wt %) at 273 K and 298 K, respectively. Moreover, the high selectivity of the polymer toward CO2 over N2 (50.6, 298 K) makes it a promising material for potential application in CO2 separation from flue gas.
    ACS Macro Letters 08/2013; 2:660-663. DOI:10.1021/mz4003485 · 5.24 Impact Factor
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    ABSTRACT: Fast synthesis of nanosized zeolite is desirable for many industrial applications. An ultrafast synthesis of LTA nanozeolite by the organic-additive-free method in a two-phase segmented fluidic microreactor has been realized. The results reveal that the obtained LTA nanozeolites through microreactor are much smaller and higher crystallinity than those under similar conditions through conventional macroscale batch reactor. By investing various test conditions, such as the crystallization temperature, the flow rate, the microchannel length, and the aging time of gel solution, this two-phase segmented fluidic microreactor system enables us to develop an ultrafast method for nanozeolite production. Particularly, when using a microreactor with the microchannel length of 20 m, it only takes 10 min for the crystallization and no aging process to successfully produce the crystalline LTA nanozeolites at 95 degrees C.
    Journal of Nanoscience and Nanotechnology 08/2013; 13(8):5736-43. DOI:10.1166/jnn.2013.7555 · 1.34 Impact Factor
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    ABSTRACT: Adsorption is an effective method for separating CO2 from flue gases. The fixed-bed adsorption and desorption of CO2 on MCM-41 and amine-modified MCM-41 (APTS-MCM-41) were studied. The dual-site Langmuir model, which considered both chemical adsorption and physical adsorption, was used to fit the experimental data. The resulting thermodynamic parameters, such as the saturated adsorption capacity, equilibrium constant, enthalpy and entropy, suggested the feasibility of the CO2 adsorption on APTS-MCM-41, as well as the reality of the adsorption mechanism. A dynamic model based on the linear driving force approximation for the mass transfer was used to describe the adsorption kinetics of CO2. The influences of the operating conditions on the breakthrough curve were investigated using both experimental and theoretical methods. Meanwhile, the impacts of changing values of the axial dispersion coefficient and the mass transfer coefficient were investigated. It showed that the amine-modified mesoporous materials would be a promising sorbent in the future CO2 capture.
    ARCHIVE Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering 1989-1996 (vols 05/2013; 227(2):106-116. DOI:10.1177/0954408912469491 · 0.55 Impact Factor

Publication Stats

324 Citations
142.02 Total Impact Points

Institutions

  • 2006–2015
    • East China University of Science and Technology
      • School of Chemistry and Molecular Engineering
      Shanghai, Shanghai Shi, China
  • 2013
    • National University of Defense Technology
      • College of Electronic Science and Engineering
      Ch’ang-sha-shih, Hunan, China