Co-reporter:Junhao Zhang, Bo Yan, Sheng Wan, and Qinghong Kong
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 16) pp:5708-5712
Publication Date(Web):March 28, 2013
DOI:10.1021/ie4004392
Polyethylene-based waste plastics need hundreds of years to degrade in atmospheric conditions, so innovative upcycling processes are necessary in addition to traditional recycling services. This study presents an environmentally benign and solvent-free autogenic process, in which waste plastics such as waste polyethylene (PE) were converted into Fe3O4@C core–shell structures with about 800 nm in diameter and tens of micrometers in length with the presence of catalysts while oxygen was absent. The composition and morphology of the as-obtained Fe3O4@C core–shell structures were characterized by advanced structural, spectroscopic, and imaging techniques. The magnetic measurement at room temperature indicates that the values of saturation magnetization (22.5 emu/g) and coercivity (152.9 Oe) of the one-dimensional Fe3O4@C core–shell structures are different from those of Fe3O4 nanoparticles and bulk Fe3O4 due to the different carbon content, dipolar interaction, size, and morphology of the products. The results indicate that the one-dimensional Fe3O4@C core/shell structures possess well acid resistance.
Co-reporter:Qinghong Kong;Hui Wu;Xingguang Zhang
Central European Journal of Chemistry 2013 Volume 11( Issue 10) pp:1682-1688
Publication Date(Web):2013 October
DOI:10.2478/s11532-013-0299-z
Co-reporter:Junhao Zhang, Bo Yan and Feng Zhang
CrystEngComm 2012 vol. 14(Issue 10) pp:3451-3455
Publication Date(Web):01 Mar 2012
DOI:10.1039/C2CE06745E
A simple one-step method to synthesize carbon-coated Fe3O4 composites with complex pine-tree-leaf structures has been developed. As revealed in FESEM and TEM analysis, the Fe3O4 nanoparticles were self-assembled to chains-like structures, which were coated by carbon shells with a thickness of about 150 nm, and the needle-like pine-tree-leaf organization grown perpendicular to the central stems are carbon nanorods. Some important preparative parameters related to the synthesis have been identified and investigated with some designed experiments. Ferromagnetic properties of the carbon-coated Fe3O4 composites with pine-tree-leaf structures have been further differentiated for the different structures, and the results show that the saturation magnetization value (18.4 emu g−1) is lower than that of bulk Fe3O4, and the coercivity value (142.3 Oe) is much higher than that of the bulk Fe3O4.
Co-reporter:Junhao Zhang, Jin Du, Hongliang Wang, Jiaolong Wang, Zhaokun Qu, Liang Jia
Materials Letters 2011 Volume 65(17–18) pp:2565-2567
Publication Date(Web):September 2011
DOI:10.1016/j.matlet.2011.05.061
Mn3O4 nanocubes were prepared by a modified autoxidation of the slurry, obtained by the reaction of manganese acetate and sodium tetraborate at room temperature. The Mn3O4 products were investigated by X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), transmission electron microscopy (TEM), etc. The results indicate that the as-synthesized products have good crystallization and Mn3O4 nanocubes with the dimensions of about 100 nm. The catalytic test shows that Mn3O4 nanocubes exhibit good catalytic performance in the oxidation of carbon monoxide. Almost 100% oxidization of carbon monoxide to carbon dioxide for the second and third runs is nearly the same to that of the first one, revealing the excellent thermal stability and recycling performance of the Mn3O4 nanocubes as catalyst.
Co-reporter:Liancheng Wang, Junhao Zhang, Liqiang Xu, Yitai Qian
Materials Research Bulletin 2011 46(10) pp: 1703-1707
Publication Date(Web):
DOI:10.1016/j.materresbull.2011.05.038
Co-reporter:JunHao Zhang;JiaoLong Wang;HongLiang Wang;Liang Jia
Science Bulletin 2011 Volume 56( Issue 30) pp:
Publication Date(Web):2011 October
DOI:10.1007/s11434-011-4653-2
High purity Fe3O4/helical carbon nanofiber composites were obtained on a large scale by the catalytic pyrolysis of ferrocene in the presence of tin powder at 500°C over 12 h. The sizes of Fe3O4 nanoparticles are 35–65 nm in size, and the diameters of the helical carbon nanofibers range from 40–70 nm. The shapes and compositions of the nanocomposites are simply controlled by adjusting the reaction temperatures. On the basis of the obtained experimental results the formation of the helical Fe3O4/carbon nanofiber composites was investigated and discussed. The magnetic hysteresis loop of the products shows ferromagnetic behavior with saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) values of ca. 29.8 emu/g, 9.6 emu/g and 306.6 Oe, respectively.
Co-reporter:Junhao Zhang;Jun Wan;Shaoxing Huang;Jin Du;Jia Zhu;Dongjing Zhang;Qinghuan Yin;Yuhui Wu
Chinese Journal of Chemistry 2010 Volume 28( Issue 9) pp:1607-1612
Publication Date(Web):
DOI:10.1002/cjoc.201090272
Abstract
The magnetic Fe3O4 microscale chains self-assembled of microoctahedrons have been synthesized via a facile one-pot solution-phase route at 200°C. The result of X-ray diffraction (XRD) indicates that the product is face-centered cubic Fe3O4 and has highly crystalline nature. Field-emission scanning electron microscopy (FESEM) and transmission electron microscope (TEM) images show that the product consists of larger numbers of Fe3O4 microoctahedrons chains, and the size of microoctahedrons is from 1 to 3 μm. The effect of NaOH concentration and solvent on the morphologies of the products indicates that appropriate alkaline surrounding and solvent may be propitious to the formation of the uniform Fe3O4 microoctahedrons chains. The magnetic measurements at room temperature indicate that the values of saturation magnetization (85.6 emu/g) and coercivity (65.2 Oe) are different from those of dispersed microoctahedrons due to the different size and the oriented self-assembled structure of microoctahedrons.
Co-reporter:Junhao Zhang, Jin Du, Yitai Qian, Qinghuan Yin, Dongjing Zhang
Materials Science and Engineering: B 2010 170(1–3) pp: 51-57
Publication Date(Web):15 June 2010
DOI:10.1016/j.mseb.2010.02.025
A shape-controlled synthesis of carbon-encapsulated Fe3O4 core/shell (Fe3O4@C) composites is reported in this paper. By tuning the reaction temperature from 500 °C to 700 °C and the amount of ammonium acid carbonate (1.0 g, 0.5 g and 2.0 g) in a sealed reaction system, Fe3O4@C composites with hexapod-like, flake-like, and chain-like morphologies have been successfully obtained using ferrocene as the precursor. Corresponding hollow carbon structures can be obtained by acid treatments. The three kinds of Fe3O4@C composites show ferromagnetic properties at room temperature, while their saturation magnetizations and coercivities are obviously different from each other, due to the various shapes and structures. Possible formation processes of these Fe3O4@C composites and corresponding hollow carbon materials are discussed. The experimental results indicate that the reaction temperature and the amount of ammonium acid carbonate play key roles in the shape-controlled synthesis of hexapod-like, flake-like and chain-like Fe3O4@C composites.
Co-reporter:Junhao Zhang, Jin Du, Yitai Qian, Shenglin Xiong
Materials Research Bulletin 2010 45(1) pp: 15-20
Publication Date(Web):
DOI:10.1016/j.materresbull.2009.09.007
Co-reporter:Junhao Zhang;Yuhui Wu;Jia Zhu;Shaoxing Huang
Central European Journal of Chemistry 2010 Volume 8( Issue 5) pp:1027-1033
Publication Date(Web):2010 October
DOI:10.2478/s11532-010-0075-2
Co-reporter:Junhao ZHANG;Xiaofang CHENG;He LIU ;Weiliang LU
Chinese Journal of Chemistry 2009 Volume 27( Issue 8) pp:1611-1616
Publication Date(Web):
DOI:10.1002/cjoc.200990272
Abstract
F-montmorillonite (F-MMT) was synthesized by a hydrothermal method at 493 K for 72 h, in which a little of hydroxyl radical is replaced by fluoride ion in the silicate structure. Poly(vinyl alcohol) (PVA)/F-MMT nanocomposites were prepared using the synthetic F-MMT by a solution-intercalation method. The F-MMT and PVA/ F-MMT nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate that the flake structured F-MMT is homogeneously dispersed in PVA, forming an exfoliated nanocomposite structure. Thermogravimetric analysis, mechanical performance and UV-visible spectroscopy were applied to test the properties of PVA nanocomposites, which indicate that the thermal stability and mechanical performance are enhanced distinctly, without a sacrifice in optical clarity. The improvement of mechanical and thermal properties was attributed to the homogeneous and good dispersion of F-MMT in polymeric matrix and the strong hydrogen bonding between O��H of PVA and F�� of F-MMT.
Co-reporter:JunHao Zhang;QingHong Kong;WeiLiang Lu;He Liu
Science Bulletin 2009 Volume 54( Issue 14) pp:2434-2439
Publication Date(Web):2009 July
DOI:10.1007/s11434-009-0248-6
Near monodisperse Fe3O4 sub-microspheres with an average diameter of 170 nm have been synthesized by a solvothermal reduction method, using K3[Fe(CN)6] as the raw material in the absence of any surfactants at 200°C for 24 h. The products were detected by XRD, FESEM, TEM, and XPS. The investigation of the reaction parameters indicates that ethylene glycol plays a key role both as reducing agent and solvent. In addition, the reaction time and temperature also have important influences on the final product. The hysteresis loop of the near monodisperse Fe3O4 sub-microspheres shows a ferromagnetic behavior with saturation magnetization of 60.8 emu/g and coercivity of 124.7 Oe.
Co-reporter:Qinghong Kong, Junhao Zhang
Polymer Degradation and Stability 2007 Volume 92(Issue 11) pp:2005-2010
Publication Date(Web):November 2007
DOI:10.1016/j.polymdegradstab.2007.08.002
Straight and helical carbon nanotubes with diameter from 20 to 60 nm have been synthesized through catalytic decomposition of polyethylene in autoclave at 700 °C. The X-ray power diffraction pattern indicates that the products are hexagonal graphite, and transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) images reveal the morphologies and structures of carbon nanotubes. The effects of reaction temperature, catalyst and maleated polypropylene on the growth of the carbon nanotubes were also discussed, and the growth mechanism of the CNTs was proposed. Pyrolysis of polyethylene is a promising green chemical method for economically producing carbon nanotubes.
