Co-reporter:Zhentao Hua, Bing Li, Leilei Li, Xiaoyu Yin, Kezheng Chen, and Wei Wang
The Journal of Physical Chemistry C 2017 Volume 121(Issue 1) pp:
Publication Date(Web):December 15, 2016
DOI:10.1021/acs.jpcc.6b08975
Hierarchical microstructured copper phosphate (HCuPO), which could accelerate water evaporation was well designed based on d–d transition of 3d electrons in Cu2+ and fabricated via a solvothermal method. A very strong vis–NIR absorption with the maximum at 808 nm was observed for the HCuPO. Upon irradiation of 808 nm NIR laser light, the HCuPO generated heat with a light-to-heat converting efficiency of 41.8%. The reason for this high efficiency was investigated and assigned to a high probability of nonradiative relaxation, which released the energy in form of heat, happened to the excited 3d electrons of Cu2+. The proposed photothermal mechanism was quite different from the surface–plasmon mechanism of other Cu-based photothermal materials. By adding HCuPO into polydimethylsiloxane (PDMS), HCuPO–PDMS composite sheets were fabricated. Due to the intrinsic hydrophobicity of PDMS matrix, the sheets were floatable on water surface and the heat generated by HCuPO was confined within water–air interface region. A much sharper temperature gradient and more rapid increase of surface temperature were observed compared with the HCuPO–water dispersion in which the HCuPO particles were dispersed in water. Porous HCuPO–PDMS sheets were fabricated in order to further accelerate water evaporation. Under 808 nm laser irradiation with power density of 1000–2000 W·m–2, water evaporation rate of salt water (3.5 wt %) was measured to be 1.13–1.85 kg·m–2·h–1 for porous floating HCuPO–PDMS, which was 2.2–3.6 times of that measured for ordinary salt water without HCuPO. By using a solar simulator as a light source, a very high solar thermal conversion efficiency of 63.6% was obtained with a power density of 1000 W·m–2, indicating that solar evaporation of salt water could be greatly enhanced by the well-designed HCuPO.
Co-reporter:Yunguo Wang, Ji Ma, Sizhi Zuo-Jiang, Kezheng Chen
Ceramics International 2017 Volume 43, Issue 18(Volume 43, Issue 18) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.ceramint.2017.09.031
In this study, conventional silicon alkaline-etching procedure was utilized to tailor magnetic properties of ε-Fe2O3/SiO2 hybrid. It was found that the saturation magnetization, coercivity and exchange bias field can be readily changed and tailored by altering the etching time and frequency in a set of sodium hydroxide solutions. The relative quantity of ε-Fe2O3 phase, the proximity or pinning effect derived from SiO2 phase as well as the phase transformation from ε-Fe2O3 to α-Fe2O3 during etching treatment were three main factors to its controllable magnetic properties. This work will shed new light on the development of functional ε-Fe2O3/SiO2 composites with tailorable magnetism in practical magnetically-relevant applications.
Co-reporter:Ji Ma, Jianxing Zhang, Chunting Liu, Kezheng Chen
Physics Letters A 2017 Volume 381, Issue 35(Issue 35) pp:
Publication Date(Web):18 September 2017
DOI:10.1016/j.physleta.2017.07.021
•Lattice strain is found to be a key factor to influence saturation magnetization.•Assembling patterns in hierarchical structures contribute to the lattice strain.•The influence of lattice strain outperforms that of non-ferromagnetic inclusions.It is unanimously accepted that non-ferromagnetic inclusions in a ferromagnetic system will lower down total saturation magnetization in unit of emu/g. In this study, “lattice strain” was found to be another key factor to have critical impact on magnetic saturation behavior of the system. The lattice strain determined assembling patterns of primary nanoparticles in hierarchical structures and was intimately related with the formation process of these architectures. Therefore, flower-necklace-like and cauliflower-like nickel hierarchical structures were used as prototype systems to evidence the relationship between assembling patterns of primary nanoparticles and magnetic saturation behaviors of these architectures. It was found that the influence of lattice strain on saturation magnetization outperformed that of non-ferromagnetic inclusions in these hierarchical structures. This will enable new insights into fundamental understanding of related magnetic effects.
Co-reporter:Kai He;Qingkun Wen;Chengwei Wang;Baoxiang Wang;Shoushan Yu;Chuncheng Hao
Soft Matter (2005-Present) 2017 vol. 13(Issue 43) pp:7879-7889
Publication Date(Web):2017/11/08
DOI:10.1039/C7SM01422H
Herein, a simple hydrothermal method is employed to synthesize anatase TiO2 with dominant (100) facets, as a precursor, using titanate nanofibers derived from alkali treatment. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) are carried out to confirm the surface morphology and phase structure of the TiO2 product. The formation mechanism of TiO2 enclosed by (100) and (101) facets is deduced to be the selective adsorption of OH− on the (100) facets of anatase TiO2. Electroheological (ER) experiments indicate that the tetragonal-facet-rod anatase TiO2 with exposed (100) facets exhibits an excellent ER performance with a high ER efficiency of up to 52.5, which results from the anisotropy of its special morphology. In addition, the effect of shape on its dielectric property is investigated via broadband dielectric spectroscopy.
Co-reporter:Kai He;Qingkun Wen;Chengwei Wang;Baoxiang Wang;Shoushan Yu;Chuncheng Hao
Soft Matter (2005-Present) 2017 vol. 13(Issue 41) pp:7677-7688
Publication Date(Web):2017/10/25
DOI:10.1039/C7SM01157A
Bowl-like titanium oxide nanoparticles were successfully prepared by a simple solvothermal method using absolute ethanol and isopropanol as the cosolvent. Ostwald ripening coupled with the inner-stress-induce effect were assumed to play an important role in the formation of this unique bowl-like morphology. The morphological evolution from solid nanosphere to bowl-like nanoparticle was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Besides, the structural characteristics of the as-synthesized TiO2 nanoparticles were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and thermogravimetric analysis (TGA). Moreover, a rotational rheometer was operated to examine the electrorheological (ER) effect. Excellent ER properties were achieved when the TiO2 particles were dispersed in silicone oil under an external electric field.
Co-reporter:Shoushan Yu, Jiaqi Wan, Kezheng Chen
Journal of Colloid and Interface Science 2016 Volume 461() pp:173-178
Publication Date(Web):1 January 2016
DOI:10.1016/j.jcis.2015.09.015
Superparamagnetic Fe3O4 supraparticles@MIL-100(Fe) core–shell nanostructure microspheres were successfully constructed by a facile step-by-step method. The polyacrylate formed in situ during the process of the preparation of Fe3O4 supraparticles not only acted as a stabilizer on the Fe3O4 nanoparticles surface, but also played a crucial role as a “bridge” in the initial stage of the framework components selectively assembly on the Fe3O4 supraparticle surfaces. The structure and composition of the obtained microspheres were characterized by SEM, TEM, DLS, XRD, FTIR, and TG analysis. The MPMS results revealed that the introduction of the MOF shells can inhibit the interplay among the neighboring Fe3O4 supraparticles while an external magnetic field applied. The well-dispersed microspheres are biocompatible, which endow the microspheres great potential in drug targeting applications with enhanced efficiency.
Co-reporter:Xiaoli Tian, Kai He, Chengwei Wang, Qingkun Wen, Baoxiang Wang, Shoushan Yu, Chuncheng Hao, Kezheng Chen, Qingquan Lei
Composites Science and Technology 2016 Volume 137() pp:118-129
Publication Date(Web):12 December 2016
DOI:10.1016/j.compscitech.2016.10.026
Anisotropic titanium oxide/polyaniline core/shell nanocomposite was synthesized via a three-step method, and its electrorheological (ER) properties under external applied electric field were researched. Firstly, monodispersed amorphous titanium oxide nanospheres were prepared by a controlled hydrolysis method and then anisotropic titanium oxide peanut-like nanospheres was obtained by using weak acid to etch the monodispersed titanium oxide sphere. At last, the surface of anisotropic TiO2 was coated with polyaniline (PANI) through an in-situ polymerization method. Then the influence factors on the preparation of anisotropic TiO2/polyaniline core/shell structure nanoparticles were discussed deeply, including different kinds and amounts of acid, the amount of aniline, and so on. The morphology and structure of the samples were characterized by scanning electron microscopy, transmission electron microscopy, zeta potential analysis and X-ray powder diffraction, respectively. The electrorheological behaviors of the anisotropic TiO2/polyaniline composite particles are characterized using a rotational rheometer, which shown a good ER activity.
Co-reporter:Shuangshuang Sun, Ji Ma, Wei Liu and Kezheng Chen
RSC Advances 2016 vol. 6(Issue 34) pp:28435-28441
Publication Date(Web):11 Mar 2016
DOI:10.1039/C6RA01175F
In this work, two-dimensional magnetite/carbon (Fe3O4@C) hybrid architectures were fabricated by a feasible template method via thermal treatment. The Fe3O4 nanoparticles were tightly embedded into the carbon sheets in the form of well-ordered arrays and disordered assembly. These architectures were then employed to remove Cr(VI) ions from water. Whatever the arrangement of Fe3O4 nanoparticles in the carbon sheets, the maximum Cr(VI) adsorption capacities were found to be around 1100 mg g−1 above 308 K in the pH range of 4.84–5.83. These values, to our knowledge, were much larger than those reported for metal-oxide adsorbents and activated carbons in the previous literature. More strikingly, these adsorbents can be easily separated from water by using a magnet. The high Cr(VI) adsorption capacities at different temperatures and easy separation are highly promising for their widespread potential applications in water treatment.
Co-reporter:Yongchao Bao
Nano-Micro Letters 2016 Volume 8( Issue 2) pp:182-192
Publication Date(Web):2016 April
DOI:10.1007/s40820-015-0076-y
The ternary plasmonic AgCl/Ag/g-C3N4 photocatalysts were successfully fabricated by a modified deposition–precipitation method, through which Ag/AgCl nanoparticles (5–15 nm in size) were evenly dispersed on the surface of g-C3N4. The AgCl/Ag/g-C3N4 composites exhibited higher photocatalytic activity than Ag/AgCl and g-C3N4. The enhanced photocatalytic performance could be attributed to an efficient separation of electron–hole pairs through a Z-scheme mechanism, in which Ag nanoparticles acted as charge separation centers.
Co-reporter:Jiaqi Wan, Ruiting Yuan, Chongyu Zhang, Ning Wu, Fengying Yan, Shoushan Yu, and Kezheng Chen
The Journal of Physical Chemistry C 2016 Volume 120(Issue 41) pp:23799-23806
Publication Date(Web):September 23, 2016
DOI:10.1021/acs.jpcc.6b06614
In this article, a simple and scalable method for preparing well-defined and highly stable colloidal dispersions of superparamagnetic iron oxide nanoparticles (IONPs) is reported. The IONPs with narrow size distribution were synthesized by polyol process. Nonhazardous sodium tripolyphosphate (STPP) was immobilized on the surface of IONPs via effective ligand exchange in aqueous phase. Then the STPP-capped IONPs were purified by tangential flow ultrafitration. The polyanionic nature of STPP and its strong coordination capability to iron oxide warrant the IONPs long-term colloidal stability even in phosphate-buffer saline. Because the ligand exchange and purification process did not involve repeated precipitation by organic solvents, the unwanted irreversible aggregation and organic impurities were avoided to the utmost extent. The absence of aggregation renders the IONPs well-defined magnetic behaviors and optimized relaxometric properties for T1-weighted magnetic resonance imaging. The in vitro cytotoxicity test suggests that the STPP-capped IONPs possess little toxicity. In vivo MRI experiment carried out with a mouse model demonstrates the excellent T1-weighted MR contrast enhancement capability of the IONPs. This new kind of IONPs is expected to be applicable in various biomedical applications.
Co-reporter:Xiaoli Tian, Kai He, Baoxiang Wang, Shoushan Yu, Chuncheng Hao, Kezheng Chen, Qingquan Lei
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 498() pp:185-193
Publication Date(Web):5 June 2016
DOI:10.1016/j.colsurfa.2016.03.054
•Complex morphological core-shell structured Fe2O3/PANI nanocomposite were synthesized via two-steps method.•Flower-like Fe2O3/polyaniline nanocomposites possess good electrorheological behavior and weak magnetism.•The obtained Fe2O3/polyaniline nanocomposite reveals an interesting combination of hierarchical and core/shell structure.Flower-like Fe2O3/polyaniline core/shell nanocomposite was obtained via a two-steps method. Firstly, monodispersed flower-like iron oxide was synthesized by a high temperature refluxing method. Then flower-like Fe2O3/polyaniline core/shell nanocomposite was further obtained via the in-situ polymerization. Scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), SQUID MPMS, UV–vis and Haake rheometer were used to investigate its structure, morphology and properties. The obtained Fe2O3/polyaniline nanocomposite reveals an interesting morphological combination of hierarchical and core/shell structure. Its electrorheological (ER) behavior were investigated using a rotational rheometer under different applied electric field strengths when dispersed in silicone oil, which shown an obvious ER activity.Complex morphological core-shell structured Fe2O3/PANI nanocomposite were synthesized via two-steps method, which can be used as a smart electrorheological materials.
Co-reporter:Baoxiang Wang, Xiaoli Tian, Kai He, Lili Ma, Shoushan Yu, Chuncheng Hao, Kezheng Chen, Qingquan Lei
Polymer 2016 Volume 83() pp:129-137
Publication Date(Web):28 January 2016
DOI:10.1016/j.polymer.2015.12.004
•Hollow polyacene quinone radical (PAQR) submicrospheres are synthesized by a modified solvothermal method.•Both the size and the shell thickness of PAQR hollow submicrospheres could be adjusted by changing the amount of SDS.•Hollow PAQR polymers exhibit smart electrorheological behaviour.Hollow polyacene quinone radical (PAQR) submicrospheres are synthesized by a modified solvothermal method. The morphology and structure of the hollow PAQR submicrospheres were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and Haake rotational rheometer, respectively. Meanwhile, both the size and the shell thickness of PAQR hollow submicrospheres could be adjusted by changing the amount of surfactant-sodium dodecyl sulfate (SDS). When PAQR hollow submicrospheres are used as the electrorheological (ER) dispersed materials, good ER effect is achieved. Furthermore, the hollow structure is beneficial to improve the anti-sedimentation property for ER application.Hollow PAQR submicrospheres with controllable sizes and shell thicknesses are easily synthesized by the solvothermal method, which can be used as a smart electrorheological materials.Download high-res image (286KB)Download full-size image
Co-reporter:Jiaqi Wan, Jing Tang, Chongyu Zhang, Ruiting Yuan and Kezheng Chen
Chemical Communications 2015 vol. 51(Issue 88) pp:15910-15913
Publication Date(Web):21 Jul 2015
DOI:10.1039/C5CC03685B
Uniform magnetite mesocrystals were fabricated by solvothermal treatment of ferrous chloride in ethylene glycol in the presence of sodium hydroxide. The formation mechanism of magnetite mesocrystals in ethylene glycol was deduced by a time-dependent experiment.
Co-reporter:Leilei Li, Kaixuan Liang, Zhentao Hua, Min Zou, Kezheng Chen and Wei Wang
Polymer Chemistry 2015 vol. 6(Issue 12) pp:2290-2296
Publication Date(Web):15 Jan 2015
DOI:10.1039/C4PY01716A
A green route to water-soluble polyaniline (PANI) using iron phosphates (FePOs) peroxidase mimic as a catalyst and H2O2 as an oxidant is presented. Polystyrene sulfonate (PSS) is used as a template to synthesize a conductive PANI-PSS complex. PANI samples were characterized by UV-Vis spectroscopy, FT-IR spectroscopy and bulk conductivity measurement. Results indicated that the conductivity of the PANI catalyzed by the FePOs peroxidase mimic greatly depends on the pH, temperature and molar ratios of H2O2 and aniline. Superior to natural horseradish peroxidase, the prepared FePOs demonstrated a robust catalytic ability and could catalyze the formation of PANI-PSS at much lower pH values of 1.5–2.6. The photothermal effect of the FePOs catalyzed PANI samples was investigated and a high light-to-heat conversion efficiency of 39.6% was obtained for the sample with a conductivity of 2.576 × 10−3 S cm−1. Excellent biocompatibility and remarkable anti-tumor effect were observed for the prepared PANI with human cervical cancer (HeLa) cells as a cell model.
Co-reporter:Hao Li, Shaoxin Song, Wei Wang and Kezheng Chen
Dalton Transactions 2015 vol. 44(Issue 36) pp:16081-16090
Publication Date(Web):05 Aug 2015
DOI:10.1039/C5DT01015B
Yb3+ and Er3+ co-doped Gd2O3 nanoparticles were synthesized via a simple homogeneous precipitation method followed by subsequent heat treatment. Morphology characterization results showed that these nanoparticles were almost spherical in shape with diameters of 200–400 nm. The particles were further modified by polyethylene glycol (PEG) to improve their suspensibility in water. The sintering temperature was found to greatly influence the fluorescent properties of the products. After calcination at 700–1200 °C, the Gd2O3:Yb,Er nanoparticles could emit bright up-conversion fluorescence under 980 nm near-infrared (NIR) laser light excitation. The mechanism of up-conversion fluorescence was studied in detail and a three-photon process was observed for both green and red up-conversion fluorescence of the Gd2O3:Yb,Er nanoparticles. Different from many other Yb3+,Er3+ co-doped up-conversion materials, the prepared Gd2O3:Yb,Er nanoparticles emitted much stronger red light than green light. The reason was investigated and ascribed to the presence of abundant hydroxyl groups on the surface of the nanoparticles as a result of PEGylation. The nanoparticles could be taken up by the human cervical cancer (HeLa) cells and presented low toxicity. Well-selected photodynamic therapy (PDT) drugs, methylene blue (MB) with a UV/Vis absorption maximum (λmax) of 665 nm and 5-aminolevulinic acid (5ALA) which is a precursor of the natural photosensitizer photoporphyrin IX (PpIX) with a λmax of 635 nm, were loaded onto the nanoparticles respectively to obtain Gd2O3:Yb,Er-MB and Gd2O3:Yb,Er-5ALA nanoparticles. Being up-conversion nanoparticles (UCNPs), the taken up Gd2O3:Yb,Er nanoparticles exposed to 980 nm laser light emitted red fluorescence which activated the loaded MB and PpIX, and then killed the HeLa cells via a PDT mechanism. In vitro therapeutic investigation evidenced the prominent PDT effects of Gd2O3:Yb,Er-MB and Gd2O3:Yb,Er-5ALA upon NIR light irradiation. In magnetic resonance imaging (MRI) studies, the relaxivity values obtained for Gd2O3:Yb,Er were r1 = 2.2705 M−1 s−1 and r2 = 3.0675 M−1 s−1 with a r2/r1 ratio close to 1, suggesting that it would be a good candidate as a positive MRI agent. It is expected that these particles have applications in magnetic-fluorescent bimodal imaging and NIR light-triggered PDT.
Co-reporter:Sen Nie, Chunsong Li, Hongrui Peng, Guicun Li and Kezheng Chen
RSC Advances 2015 vol. 5(Issue 30) pp:23278-23282
Publication Date(Web):26 Feb 2015
DOI:10.1039/C4RA16475J
Ti3+ self-doped Li4Ti5O12 (S-LTO) nanosheets have been synthesized via a facile solvothermal approach combined with hydrogenation treatment. The thickness and lateral dimension of Li4Ti5O12 nanosheets are 10–20 nm and 100–400 nm, respectively. The Ti3+ species and/or oxygen vacancies are well introduced into the crystal structures of Li4Ti5O12 after hydrogen reduction, resulting into an enhancement in the electronic conductivity and the modified surface electrochemical activity. When evaluated for lithium storage capacity, the S-LTO nanosheets exhibit enhanced electrochemical energy storage performances compared to the pristine Li4Ti5O12 (P-LTO) nanosheets, including high capacity (165.6 mA h g−1 at 0.5 C), excellent rate capability (119.6 mA h g−1 at 20 C), and good cyclic stability (95.3% capacity retention after 100 cycles at 10 C). The improvement of lithium storage performances is ascribed to the increased electronic conductivity and the shortened lithium ion diffusion paths arising from the introduction of Ti3+ species and the ultrathin thickness of S-LTO.
Co-reporter:Xiaoli Tian;Yichao Yin;Baoxiang Wang;Xianfen Song;Shuangshuang Sun;Shoushan Yu;Chuncheng Hao
European Journal of Inorganic Chemistry 2015 Volume 2015( Issue 3) pp:430-440
Publication Date(Web):
DOI:10.1002/ejic.201402816
Abstract
α-Fe2O3@TiO2 core–shell nanoparticles were prepared through a combination of reflux and hydrolysis methods. Firstly, a spindle-like and monodispersed α-Fe2O3 nanorod core was fabricated by using a reflux method. In the second step, an amorphous TiO2 shell was coated onto the surface of the nonspherical α-Fe2O3 core with a uniform thickness by means of a controlled hydrolysis method. The morphology, structure, and electrorheological (ER) activity of α-Fe2O3@TiO2 core–shell nanoparticles were determined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), magnetic testing, and by using a rotational rheometer. The resulting nonspherical core–shell nanoparticles possess the advantages of uniform sizes, weak magnetism, and smart electrorheological behavior. An enhanced ER effect is found with the α-Fe2O3@TiO2 and hollow TiO2 ER suspension compared with that of a pure α-Fe2O3 ER suspension.
Co-reporter:Ji Ma;Lianchao Han
Science China Chemistry 2015 Volume 58( Issue 4) pp:620-626
Publication Date(Web):2015 April
DOI:10.1007/s11426-014-5298-1
In this work, surface-mazelike ZnO, Cu, and Ni hierarchical structures were synthesized via a versatile ethylene glycol-mediated solvothermal method. The structure evolution of these materials bore striking similarities, including (1) initial formation of metal alkoxides precursors and (2) subsequent structural evolution of products from tiered plates to jigsaw puzzles; then to extrusion ridges, nests and spindles; and thereafter to final mazelike structures driven by persistent thermal decomposition of preformed precursors. Based on their unique surface morphologies in sinuous asymmetry, it is anticipated that such mazelike hierarchical structures may shed new light on the development of morphology-controlled adsorption and heterogeneous catalysts.
Co-reporter:Xiaobing Zhang;Ji Ma
Nano-Micro Letters 2015 Volume 7( Issue 4) pp:360-367
Publication Date(Web):2015 October
DOI:10.1007/s40820-015-0051-7
In this study, the impact of morphology of conductive agent and anode material (Fe3O4) on lithium storage properties was throughly investigated. Granular and belt-like Fe3O4 active materials were separately blended with two kinds of conductive agents (i.e., granular acetylene black and multi-walled carbon nanotube) as anodes in lithium-ion batteries (LIBs), respectively. It was found that the morphology of conductive agent is of utmost importance in determining LIBs storage properties. In contrast, not as the way we anticipated, the morphology of anode material merely plays a subordinate role in their electrochemical performances. Further, the morphology-matching principle of electrode materials was discussed so as to render their utilization more rational and effective in LIBs.
Co-reporter:Shuxian Wang, Jing Tang, Hongfu Zhao, Jiaqi Wan, Kezheng Chen
Journal of Colloid and Interface Science 2014 Volume 432() pp:43-46
Publication Date(Web):15 October 2014
DOI:10.1016/j.jcis.2014.06.062
•Core–shell Fe3O4@SiO2 nanoparticles were fabricated by direct silicon oxidation.•The silica coating method is green, facile and low cost without using TEOS.•The products have desirable characteristics for T2 MRI contrast agents.Magnetite–silica core–shell nanoparticles (Fe3O4@SiO2 NPs) were prepared from silicon powder by direct oxidation without using any expensive precursors (such as TEOS) and organic solvents. The as-prepared Fe3O4@SiO2 NPs were characterized by TEM, DLS, XRD, FT-IR, zeta potential and NMR Analyzer. The results show that the Fe3O4@SiO2 NPs are monodispersed core–shell nanostructures with single cores that were uniformly coated by silica shells. The relaxation property indicates that Fe3O4@SiO2 NPs have desirable characteristics for T2 MRI contrast agents. This facile and green method is promising for large-scale production, which would open new opportunities for preparing core–shell nanostructures for biomedical applications.Graphical abstract
Co-reporter:Ji Ma, Xiaodan Zhang, Kezheng Chen and Xiaodong Han
RSC Advances 2014 vol. 4(Issue 18) pp:9166-9171
Publication Date(Web):21 Jan 2014
DOI:10.1039/C3RA47318J
The over capacity of lithium ion batteries with metal-oxides anode materials is usually regarded as originating from the low-voltage decomposition of the electrolyte and subsequent formation of a gel-like polymer layer deposited on the metal-oxides surfaces. In this work, we report a high over capacity value of 1800 mA h g−1 after 350th charge–discharge cycles for Fe2O3-made lithium ion batteries. It is found that the capacitive nature of the designed Fe2O3@C18H34O2 nanostructure not only contributes to the large observed excess in capacity, but also results in unique rate capabilities. Thus, a capacitive model is proposed to outline a plausible mechanism to explain these electrochemical findings, and it is anticipated that this paper will shed some new light on future design of the next generation of lithium ion batteries.
Co-reporter:Zhenfang Zhou, Zhonghua Zhang, Hongrui Peng, Yong Qin, Guicun Li and Kezheng Chen
RSC Advances 2014 vol. 4(Issue 11) pp:5524-5530
Publication Date(Web):17 Dec 2013
DOI:10.1039/C3RA45076G
Nitrogen- and oxygen-containing activated carbon nanotubes have been successfully synthesized via a high temperature carbonization of polypyrrole (PPy) nanotubes followed by chemical activation. The first carbonization step ensures the formation of amorphous carbon nanotubes, which are more stable than PPy to preserve the nanotube morphology during the subsequent chemical activation process. The obtained activated carbon nanotubes with high nitrogen (19.8 wt%) and oxygen contents (11.1 wt%) show enlarged specific areas of 705.9 m2 g−1 compared to that of the pristine carbon nanotubes (212.4 m2 g−1). As expected, the activated carbon nanotubes exhibit enhanced capacitance properties, such as an enlarged specific capacity (384.9 F g−1 at 0.5 A g−1), excellent rate capability (201 F g−1 at 50 A g−1), and more stable cyclic stability (only 2.4% of specific capacitance loss after 500 cycles) due to its abundant micropores, high specific areas and abundant interfacial functional groups. This method is facile, low cost and enables easy production of large quantities, and can be expected to open up new opportunities in designing high-performance carbon electrode materials for supercapacitors.
Co-reporter:Yuanlu Yao, Huaicheng Liu, Guicun Li, Hongrui Peng, Kezheng Chen
Materials Chemistry and Physics 2014 Volume 143(Issue 2) pp:867-872
Publication Date(Web):15 January 2014
DOI:10.1016/j.matchemphys.2013.10.028
•Multi-shelled LiNi0.5Mn1.5O4 microspheres were prepared by a co-precipitation method.•The formation mechanism of multi-shelled LiNi0.5Mn1.5O4 microspheres was illustrated.•Multi-shelled LiNi0.5Mn1.5O4 microspheres exhibited good electrochemical performances.Multi-shelled porous LiNi0.5Mn1.5O4 microspheres have been successfully synthesized by a co-precipitation approach combined with high-temperature calcinations. The compositions and structures of multi-shelled LiNi0.5Mn1.5O4 microspheres have been investigated by a variety of characterization methods. The LiNi0.5Mn1.5O4 microspheres are composed of a lot of concentric circular porous shells with constant O, Mn, and Ni concentration, which is ascribed to the fast outward diffusion of Mn and Ni atoms and the slow inward diffusion of O and Li atoms during the calcination process. Electrochemical measurements show that LiNi0.5Mn1.5O4 microspheres deliver good cycling stability and rate capability with discharge capacities of 137.1 (0.1 C), 133.9 (0.2 C), 124.2 (0.5 C), 114.9 (1 C), and 96.0 mAh g−1 (2 C). The LiNi0.5Mn1.5O4 microspheres synthesized by the facile method may be a promising cathode candidate for high energy density lithium-ion batteries.
Co-reporter:Baoxiang Wang, Xiaoli Tian, Xianfen Song, Lili Ma, Shoushan Yu, Chuncheng Hao, Kezheng Chen, Qingquan Lei
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 461() pp:184-194
Publication Date(Web):5 November 2014
DOI:10.1016/j.colsurfa.2014.07.046
•Cr-doped FeBiO3 nanoparticles were synthesized with a modified sol–gel method.•The Cr-doped FeBiO3 ER fluid showed notable electrorheological activity.•The high dielectric properties can induce stronger ER behavior.A series of Cr-doped multiferroelectric FeBiO3 nanoparticles were synthesized via a facile sol gel method. The resultant Cr-doped FeBiO3 was characterized by means of different techniques, such as scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and electrorheological (ER) tests. Under an external electric field, electrorheological properties of the suspension containing such Cr-doped and undoped FeBiO3 particles were investigated by steady shear experiments. It was found that the suspension of Cr-doped FeBiO3 particles possesses a better ER effect than that of pure FeBiO3 particles. Furthermore, different Cr-doped concentration plays an important role on the ER behavior. Combining the dielectric analysis, the enhanced ER effect of Cr-doped FeBiO3 suspension can be attributed to the improved interfacial polarization.
Co-reporter:Leilei Li ; Wei Wang
The Journal of Physical Chemistry C 2014 Volume 118(Issue 45) pp:26351-26358
Publication Date(Web):October 21, 2014
DOI:10.1021/jp507660u
Black elemental selenium (Se), which shows peroxidase mimic activity and can catalyze the redox reaction between H2O2 and tetramethylbenzidine (TMB) was prepared by a simple method. The mimetic activity was greatly influenced by pH and temperature. The black elemental Se was used to catalyze the green synthesis of water-soluble polypyrrole (PPy) in the presence of sodium poly(styrene sulfonate) (PSS) as the template. The ultraviolet–visible (UV–vis) spectra of PPy obtained at different pH and temperature were recorded to obtain the optimum conditions. The black elemental Se catalyzed PPy can convert near-infrared (NIR) light energy to heat with a photothermal efficiency of 28.4%. After exposure to 808 nm laser light irradiation for 10 min, a remarkable antitumor effect was observed for human cervical cancer (HeLa) cells cocultured with the PPy.
Co-reporter:Zhonghua Zhang, Guicun Li, Hongrui Peng and Kezheng Chen
Journal of Materials Chemistry A 2013 vol. 1(Issue 48) pp:15429-15434
Publication Date(Web):22 Oct 2013
DOI:10.1039/C3TA13860G
Hierarchical hollow microspheres composed of N-doped carbon coated Li4Ti5O12 nanosheets (NC-LTO) have been synthesized on a large scale by a facile low-temperature solution-based approach combined with high temperature calcination. The primary Li4Ti5O12 nanosheets show zigzag morphology with a typical thickness of about 5.0 nm, which are uniformly coated with N-doped carbon layers. When evaluated for lithium storage capacity, the NC-LTO hollow microspheres display enhanced electrochemical energy storage performances compared to the pristine hollow microspheres composed of Li4Ti5O12 nanosheets (A-LTO), including high capacity (181.4 mA h g−1 at 0.5 C), excellent rate capability (140.8 mA h g−1 at 20 C), and good cyclic stability (92.8% capacity loss after 100 cycles at 20 C). The reasons for these improvements are explored in terms of the increased electronic conductivity and the facilitation of lithium ion transport arising from the introduction of N-doped carbon layers and the thin zigzag Li4Ti5O12 nanosheets.
Co-reporter:Ji Ma, Xiaodan Zhang, Kezheng Chen, Guicun Li and Xiaodong Han
Journal of Materials Chemistry A 2013 vol. 1(Issue 18) pp:5545-5553
Publication Date(Web):28 Feb 2013
DOI:10.1039/C3TA10396J
A series of hematite hierarchical structures, including amorphous hierarchical spheres with varied internal polycrystalline structures, single-crystalline nanoflakes and co-aligned micro-layered structures, have been fabricated by simply controlling the reaction time in a one-step hydrothermal procedure. In the early stages of the reaction, an Ostwald ripening process dominates the successive occurrence of single-shell, double-shell and yolk–shell spheres, which reoccur in reverse order under the effect of an H+ etching process on prolonging the reaction time. Afterwards, the oriented attachment mechanism takes charge of the formation of single-crystalline nanoflakes and co-aligned micro-layered structures at the expense of the previously formed spheres. It is found that the different adsorption configuration of the hydroxyl groups in different crystallographic planes is of fundamental importance to the morphology evolution from nanoflakes to micro-layered structures. The electrochemical measurements of these hierarchical structures show that their lithium storage properties are closely related to their crystallinity and morphology. The amorphous-based architectures exhibit quite similar electrochemical properties regardless of their morphologies, whereas the crystallized architectures present morphology-dependent electrochemical properties. Also, well-crystallized electrodes facilitate the access of lithium-ions and thus possess superior lithium storage performances, whether in the initial charge–discharge cycling or in the subsequent cyclic capacity retention.
Co-reporter:Yuanlu Yao, Huaicheng Liu, Guicun Li, Hongrui Peng, Kezheng Chen
Electrochimica Acta 2013 Volume 113() pp:340-345
Publication Date(Web):15 December 2013
DOI:10.1016/j.electacta.2013.09.071
•Porous LiNi1/3Co1/3Mn1/3O2 microspheres were prepared by a co-precipitation method.•Phosphate coating layer was formed by H3PO4 etching and then annealing treatment.•Phosphate-coated LiNi1/3Co1/3Mn1/3O2 exhibited good electrochemical performances.Porous LiNi1/3Co1/3Mn1/3O2 microspheres were synthesized by a co-precipitation approach combined with high-temperature calcination. To improve the electrochemical performances, phosphate coating was formed on the surfaces of porous LiNi1/3Co1/3Mn1/3O2 microspheres by H3PO4 etching and subsequent annealing treatment. As anticipated, phosphate-coated LiNi1/3Co1/3Mn1/3O2 microspheres (2 mol.% H3PO4) delivered discharge capacity of 100. 1 mAh g−1 at 5 °C, which was higher than that of pristine LiNi1/3Co1/3Mn1/3O2 microspheres (64.8 mAh g−1). The improvement of rate capability and cycle stability of LiNi1/3Co1/3Mn1/3O2 microspheres could be attributed to the phosphate coating, which suppressed the side reaction between cathode and electrolyte. The phosphate surface modification has a promising application in improving the performance of layered oxide cathode materials for lithium ion batteries.
Co-reporter:Yichao Yin, Chenjie Liu, Baoxiang Wang, Shoushan Yu and Kezheng Chen
Dalton Transactions 2013 vol. 42(Issue 19) pp:7233-7240
Publication Date(Web):07 Mar 2013
DOI:10.1039/C3DT32559H
A simple, one-pot solvothermal method has been demonstrated for the preparation of bifunctional Fe3O4@titanium oxide core/shell nanoparticles. In a typical procedure, tetraalkoxyl titanium Ti(OC4H9)4 and FeCl3 as precursors were added into ethylene glycol and further solvothermal treatment was used to synthesize the core/shell particles. The core/shell particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), SQUID MPMS and rheometry. The morphological results showed titanium oxide nanorods with 100–200 nm length and 10–20 nm diameter coated on the surface of 200–300 nm Fe3O4 submicrospheres. Reaction time, the titanium source, the barium salt etc. have an influence on the morphology of core/shell particles. The core/shell particles can not only respond to an external magnetic field, but also to an electric field – a novel application of electrorheological fluid.
Co-reporter:Li Wang, Xinghao Zhang and Kezheng Chen
CrystEngComm 2013 vol. 15(Issue 24) pp:4860-4864
Publication Date(Web):04 Apr 2013
DOI:10.1039/C3CE40134K
Three-dimensional (3D) hierarchical porous ZnO architectures constructed by sheet-like structures were prepared through calcination of a bilamellar basic zinc citrate intermediate. The molar ratio of citrate anion/Zn2+ and the pH value of the reaction solution play crucial roles in the formation of the 3D hierarchical nanostructures. On the basis of the synthetic experimental results, a growth mechanism is proposed in the case of citrate as the organic ligand. The resulting nano-scaled porous ZnO structures exhibit a high specific surface area up to 55.6 m2 g−1 with a pore size of 5.1 nm. A light-to-electricity conversion efficiency of 4.46% was achieved of the dye-sensitized solar cells with the porous ZnO as the photoanode.
Co-reporter:Yong Wang, Ji Ma and Kezheng Chen
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 44) pp:19415-19421
Publication Date(Web):01 Oct 2013
DOI:10.1039/C3CP52867G
A novel hollow urchin-like α-FeOOH hierarchical structure was fabricated via a one-pot hydrothermal procedure without using any templates, surfactants or organic raw materials. An inside-out amorphous ripening mechanism was proposed to unravel its structural evolution. The kinetics, equilibrium and thermodynamics of its adsorptive removal of Cr(VI) from wastewater were comprehensively investigated. It was found that the adsorption process can be depicted using a pseudo-second-order model, and a high adsorption capacity of 58.97 mg g−1 was obtained from the equilibrium adsorption isotherm. Also, the thermodynamic parameters (i.e., enthalpy, entropy and Gibbs free energy) at different temperatures were acquired to reveal a spontaneous adsorption process, with both physical and chemical characteristics.
Co-reporter:Baoxiang Wang, Yichao Yin, Chenjie Liu, Shoushan Yu and Kezheng Chen
Dalton Transactions 2013 vol. 42(Issue 27) pp:10042-10055
Publication Date(Web):30 Apr 2013
DOI:10.1039/C3DT50504A
Flower-like BaTiO3/Fe3O4 hierarchically structured particles composed of nano-scale structures on micro-scale materials were synthesized by a simple solvothermal approach and characterized by the means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), magnetic testing and rotary viscometer. The influences on the morphology and structure of solvothermal times, type and amount of surfactant, EG:H2O ratio, etc. were studied. Magnetic testing results show that the samples have strong magnetism and they exhibit superparamagnetic behavior, as evidenced by no coercivity and the remanence at room temperature, due to their very small sizes, observed on the M–H loop. The saturation magnetization (Ms) value can achieve 18.3 emu g−1. The electrorheological (ER) effect was investigated using a suspension of the flower-like BaTiO3/Fe3O4 hierarchically structured particles dispersed in silicone oil. We can observe a slight shear-thinning behavior of shear viscosity at a low shear rate region even at zero applied electric field and a Newtonian fluid behavior at high shear rate regions.
Co-reporter:Xiaojun Wei, Wei Wang and Kezheng Chen
Dalton Transactions 2013 vol. 42(Issue 5) pp:1752-1759
Publication Date(Web):29 Oct 2012
DOI:10.1039/C2DT31783D
As bimodal magnetic-fluorescent imaging agents, the preparation of ZnS:Tb,Gd and ZnS:Er,Yb,Gd nanoparticles via a facile homogeneous precipitation method is reported. The results show that these nanoparticles are almost spherical in shape with a diameter of 100–200 nm approximately and a major phase of wurtzite-structured ZnS. The products can successfully label the human hepatocellular carcinoma (HepG2) cells and present low toxicity even at concentrations up to 5 mg mL−1. Additionally, for the ZnS:Er,Yb,Gd nanoparticles calcinated above 950 °C, NIR-to-visible up-conversion fluorescence were obtained, which is believed to be superior to traditional ZnS-based bioimaging agents with down conversion. In MRI studies, they reveal a longitudinal relaxivity rate (r1) of 39.46 mM−1 s−1 and 57.8 mM−1 s−1, respectively, which are much larger than the conventional Gd-DTPA and currently reported Gd-base nanoparticles, suggesting great potential as MRI agents.
Co-reporter:Baoxiang Wang, Chenjie Liu, Yichao Yin, Shoushan Yu, Kezheng Chen, Pengbo Liu, Bing Liang
Composites Science and Technology 2013 Volume 86() pp:89-100
Publication Date(Web):24 September 2013
DOI:10.1016/j.compscitech.2013.07.003
Monodispersed titanium oxide nanospheres were synthesized via the controlled hydrolysis method in this study firstly. Then the rapid mixing method was used to in situ oxidation polymerize aniline, which can modify the surface of titanium oxide nanospheres to form a core/shell nanostructure. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and rotational viscometer were used to investigate its structure, morphology and properties. The different type and dosage of surfactants, different acids, crystal forms of titanium oxide and different dosages of aniline were studied to analysis the impact on the TiO2/PANI nanocomposites. The suitable type and dosage of surfactants, the ratio of aniline to titania were the key to synthesize the nanocomposite, which can include nanoring, nanofiber or nanoparticles core/shell composite depending the synthesis condition. The titania/polyaniline composite showed typical electrorheological (ER) behavior, which demonstrated its potential applications as an ER smart material.
Co-reporter:Xiao-Yan Sun;Shou-Shan Yu;Jia-Qi Wan ;Ke-Zheng Chen
Journal of Biomedical Materials Research Part A 2013 Volume 101A( Issue 2) pp:607-612
Publication Date(Web):
DOI:10.1002/jbm.a.34343
Abstract
Magnetite (Fe3O4) nanoparticles with the surface hydroxyl groups were achieved by a polyol process. Using 2-(4-chlorosulfonylphenyl) ethyltrichlorosilane (CTCS) as initiator, 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) as monomer, poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC)-grafted Fe3O4 nanoparticles (MNP) were successfully prepared via the atom transfer radical polymerization (ATRP) method. The successful grafting of PMPC on the Fe3O4 nanoparticles surface was ascertained from the FTIR analysis. The modified nanoparticles (MNP-CTCS-PMPC) showed a good biocompatibility in the cytotoxicity test in vitro. Performance testing of MNP-CTCS-PMPC was performed through magnetic resonance analysis (MR), and its r2/r1 value was 24.1. These results indicated that the modified Fe3O4 nanoparticles would be a potential MRI contrast reagent. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Co-reporter:Guicun Li, Zhonghua Zhang, Hongrui Peng and Kezheng Chen
RSC Advances 2013 vol. 3(Issue 29) pp:11507-11510
Publication Date(Web):24 May 2013
DOI:10.1039/C3RA41858H
Mesoporous hydrogenated TiO2 microspheres were synthesized via a simple hydrogenation treatment process, and showed twice the rate capability compared to that of mesoporous TiO2 microspheres at 20 C due to the combination of the short lithium ion diffusion path and the high electronic conductivity of the mesoporous hydrogenated TiO2 framework.
Co-reporter:Baoxiang Wang;Chenjie Liu;Yichao Yin;Xiaoli Tian;Shoushan Yu;Pengbo Liu;Bing Liang
Journal of Applied Polymer Science 2013 Volume 130( Issue 2) pp:1104-1113
Publication Date(Web):
DOI:10.1002/app.39262
ABSTRACT
A novel polyaniline nanofiber/kaolinite nanoplatelet hybrid nanocomposite was synthesized by means of rapidly mixed in situ polymerization. The resultant polyaniline/kaolinite hybrid nanocomposite was characterized via different techniques, such as X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results show that 2D clay nanoplatelets are coated by the 1D polyaniline nanofibers. The nanoclay platelets can improve the thermal stability of polyaniline nanofibers. An electrorheological effect is found with the suspension of polyaniline nanofiber/kaolinite nanoplatelet hybrid nanocomposite dispersed in silicone oil. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1104-1113, 2013
Co-reporter:Shuyuan Ju, Tao Liu, Hongrui Peng, Guicun Li, Kezheng Chen
Materials Letters 2013 Volume 93() pp:194-198
Publication Date(Web):15 February 2013
DOI:10.1016/j.matlet.2012.11.083
Porous spherical LiFePO4/C microscale secondary particles have been synthesized by the low-temperature hydrothermal method combined with high-temperature calcinations. The synthetic method is facile and easy to scale-up. The spherical microscale secondary particles (5–6 μm) with porous structures are composed of carbon-coated primary nanoparticles (40–80 nm), which posses high electronic conductivity, short lithium ion diffusion paths, and high tap density of approximately 1.4 g cm−3. The product delivers desirable electrochemical performances, such as a high rate capacity of 95 mA h g−1 at 5C and stable cycle life. The LiFePO4 electrode with desired features is a promising cathode candidate for high-power rechargeable lithium-ion batteries.Highlights► Porous spherical LiFePO4/C microparticles have been synthesized via a novel route. ► LiFePO4/C microparticles have high tap density of approximately 1.4 g cm−3. ► LiFePO4/C microparticles deliver desirable electrochemical performances.
Co-reporter:Li Wang
Crystal Research and Technology 2013 Volume 48( Issue 3) pp:163-168
Publication Date(Web):
DOI:10.1002/crat.201300029
Abstract
Pencil-like ZnO nanostructure was synthesized by directly oxidizing granular Zn films, which was thermal deposited in a nitrogen atmosphere from Zn powder in a horizontal tube furnace. The formation of the pencil-like structure, including a hexagonal rod and a sharp tip with diameter about 60 nm, highly depend on the thickness of the initial zinc film and the temperature of the oxidizing process. ZnO nanorods were formed in a relatively low temperature, while thicker zinc film was apt to form a dense ZnO film with tubular structures. The different structured ZnO materials showed distinguishing optical properties which indicate the intrinsic defects forming in the different growth conditions. The pencil-like ZnO structures exhibit a relatively strong green emission attributed to the high concentrations of oxygen vacancies and its taper tip has great prospects in field-emission devices.
Co-reporter:Xiaojun Wei, Wei Wang, and Kezheng Chen
The Journal of Physical Chemistry C 2013 Volume 117(Issue 45) pp:23716-23729
Publication Date(Web):October 18, 2013
DOI:10.1021/jp4071696
In this paper, fluorescent and magnetic bifunctional ZnO:Er,Yb,Gd particles were synthesized via a simple homogeneous precipitation method. The morphology, size, fluorescent properties, and magnetic properties of the particles can be readily modified by doping with Er3+, Yb3+, and Gd3+. The results revealed that the ZnO:Er,Yb,Gd particles have both down-conversion and up-conversion fluorescence after calcination at high temperatures (>700 °C). The products successfully labled the human hepatocellular carcinoma (HepG2) cells and presented low toxicity even at a high concentration of 2 mg/mL. Being upconverting nanoparticles (UCNPs), the prepared ZnO:Er,Yb,Gd particles exposed to 980 nm near-infrared (NIR) laser light emitted up-conversion fluorescence which could be absorbed by a photodynamic therapy (PDT) drug, methylene blue (MB), and then killed the HepG2 cells via PDT mechanism. In vitro therapeutic investigation evidenced the prominent PDT effects of MB-loaded ZnO:Er,Yb,Gd UCNPs upon NIR light irradiation. In magnetic resonance imaging (MRI) studies, ZnO:Er,Yb,Gd particles revealed a tunable longitudinal relaxivity rate (r1) from 23.03 mM–1 s–1 to 36.84 mM–1 s–1, which is much larger than the conventional Gd-DTPA and currently reported Gd-base nanoparticles, suggesting it would be a good candidate as an MRI agent. It is expected that these particles have applications in magnetic-fluorescent bimodal imaging and NIR light triggered photodynamic therapy.
Co-reporter:Jiaqi Wan, Xuehui Jiang, Hui Li and Kezheng Chen
Journal of Materials Chemistry A 2012 vol. 22(Issue 27) pp:13500-13505
Publication Date(Web):09 May 2012
DOI:10.1039/C2JM30684K
Monodisperse ZnFe2O4 nanoparticles were synthesized using a simple and low-cost polyol process based on thermal decomposition of the precursors of Fe(acac)3 and Zn(acac)2 in triethylene glycol without any surfactant. The as-prepared ZnFe2O4 nanoparticles are highly crystalline, uniform in size, superparamagnetic and can be easily dispersed in aqueous media due to being coated by a layer of hydrophilic polyol ligands in situ. Magnetic study shown that the ZnFe2O4 nanoparticles had a low magnetic anisotropy and low magnetic moment compared to the conventional Fe3O4 nanoparticles. As a result, the as-prepared ZnFe2O4 nanoparticles provide an optimized r2/r1 ratio for T1-weighted magnetic resonance imaging (MRI) in the clinical field strength. A preliminary in vitro cytotoxicity test suggests that the zinc ferrite nanoparticles possess a good safety profile. Therefore, the as-prepared ZnFe2O4 nanoparticles have great potential to serve as a novel non-lanthanide T1 MRI contrast agent.
Co-reporter:Wei Wang, Xiangpeng Jiang and Kezheng Chen
Chemical Communications 2012 vol. 48(Issue 54) pp:6839-6841
Publication Date(Web):16 May 2012
DOI:10.1039/C2CC32328A
Solvothermally synthesized CePO4:Tb,Gd hollow nanospheres were fabricated as a peroxidase mimic and bimodal magnetic–fluorescent imaging agent, which show potential applications in biocatalysis and bioimaging.
Co-reporter:Wei Wang, Xiangpeng Jiang and Kezheng Chen
Chemical Communications 2012 vol. 48(Issue 58) pp:7289-7291
Publication Date(Web):23 May 2012
DOI:10.1039/C2CC32429F
Novel iron phosphates microflowers which show SOD-like and peroxidase-like mimic activities were prepared, suggesting potential applications as a biocatalyst and a biosensor for H2O2.
Co-reporter:Wei Wang, Xiangpeng Jiang and Kezheng Chen
Dalton Transactions 2012 vol. 41(Issue 2) pp:490-497
Publication Date(Web):31 Oct 2011
DOI:10.1039/C1DT11200G
Lanthanide-doped chitosan nanospheres (LDCNs) and lanthanide-Fe3O4-doped chitosan nanospheres (Fe3O4-LDCNs) are fabricated and show fluorescence, MRI effectiveness and desirable biocompatibility. Superior to most nanoparticles that were found retained in cytoplasmic organelles rather than the nucleus, the prepared chitosan nanospheres preferentially enter and illuminate the cell nuclei. Complexation of plasmid DNA (pDNA) to the nanospheres was accomplished via electrostatic forces between positively charged chitosan and negatively charged pDNA. Satisfactory results of the complexation indicate that the prepared chitosan nanospheres can serve as a potential fluorescent nonviral vector for pDNA delivery that can fulfill gene delivery and transfer efficiency assessment simultaneously, without an additional step of tagging fluorophores to the vectors carried out in fabrications of currently available pDNA delivery vectors.
Co-reporter:Yongjiang Sun, Li Wang, Xuegang Yu and Kezheng Chen
CrystEngComm 2012 vol. 14(Issue 9) pp:3199-3204
Publication Date(Web):02 Mar 2012
DOI:10.1039/C2CE06335B
A novel flower-like 3D ZnO superstructure with high uniformity was fabricated on a large scale through a facile aqueous solution route at room temperature. The as-prepared ZnO superstructures with a diameter of about 3 μm are assembled by large amounts of interleaving nanosheets, which have a uniform thickness of about 15 nm and a well-crystalline structure with {100} planes as basal facets. The hierarchical microstructures, which were formed via a two-stage nucleation–growth process, highly depend on the concentration of NaOH and trisodium citrate dihydrate. The photoluminescence result indicates that the ZnO superstructures possess a relatively strong UV emission. The photodecomposition of methyl orange indicates that such ZnO superstructures possess excellent photocatalytic activity.
Co-reporter:Yan Li, Hongrui Peng, Guicun Li, Kezheng Chen
European Polymer Journal 2012 Volume 48(Issue 8) pp:1406-1412
Publication Date(Web):August 2012
DOI:10.1016/j.eurpolymj.2012.05.014
Sandwich-like polyaniline/graphene composite nanosheets have been synthesized by chemical oxidation polymerization of aniline monomer on the surfaces of reduced graphene oxide nanosheets in the absence of any surfactants. The influences of the mass ratios of aniline and reduced graphene oxide on the sizes and morphologies of polyaniline/graphene nanocomposites have been investigated. As the mass ratio of aniline and reduced graphene oxide is smaller than 12:1, polymerization reaction of aniline occurs on the surfaces of reduced graphene oxide by heterogeneous nucleation to form sandwich-like polyaniline/graphene composite nanosheets. However, besides sandwich-like polyaniline/graphene composite nanosheets, polyaniline nanofibers are formed by homogeneous nucleation. In comparison with reduced graphene oxide and polyaniline nanofibers, the obtained sandwich-like polyaniline/graphene composite nanosheets exhibit good electrochemical performances due to the synergistic effect between graphene and polyaniline.Graphical abstractSandwich-like polyaniline/graphene composite nanosheets have been synthesized by chemical oxidation polymerization of aniline monomer on the surfaces of reduced graphene oxide nanosheets, which exhibit good electrochemical performances due to the synergistic effect between graphene and polyaniline.Highlights► Sandwich-like polyaniline/graphene composite nanosheets were synthesized. ► The heterogeneous nucleation mechanism of polyanilne was proposed. ► The specific capacitances and capacitance retention were remarkably enhanced.
Co-reporter:Shuyuan Ju, Hongrui Peng, Guicun Li, Kezheng Chen
Materials Letters 2012 Volume 74() pp:22-25
Publication Date(Web):1 May 2012
DOI:10.1016/j.matlet.2012.01.058
Olivine LiFePO4 single-crystalline nanoplates with large exposure of bc-planes have been synthesized by a facile solvothermal method. The thin side of LiFePO4 nanoplates is along the a-axis, differing from that along b-axis or c-axis reported previously. The thickness, width, and length of LiFePO4 nanoplates are about 20–30 nm, 120–160 nm, and 120–250 nm, respectively. The synthesis of LiFePO4 single-crystalline nanoplates dominated with bc-planes is important for understanding the growth habit of LiFePO4 crystal. After coated with carbon, the LiFePO4/C composite nanoplates exhibit good electrochemical performances with discharge capacities of 163 (0.1C), 154 (0.5C), 146 (1C), 130 (2C), and 96 mAh g− 1 (5C).Highlights► LiFePO4 single-crystalline nanoplates have been synthesized by solvothermal method. ► The thin side of LiFePO4 nanoplates is along the a-axis. ► The LiFePO4/C composite nanoplates exhibit good electrochemical performances.
Co-reporter:Xuegang Yu, Yan Shan, Guicun Li and Kezheng Chen
Journal of Materials Chemistry A 2011 vol. 21(Issue 22) pp:8104-8109
Publication Date(Web):28 Apr 2011
DOI:10.1039/C1JM10622H
Bifunctional magnetic–optical Fe3O4@SiO2@Y2O3:Yb3+,Er3+ near-infrared-to-visible up-conversion nanoparticles (UCNPs) with core–shell structures have been successfully fabricated by a facile layer-by-layer method. The presented materials were characterized by XRD, FTIR, TEM, fluorescence spectrophotometer, NMR Analyzer and SQUID MPMS. The results showed that the Fe3O4 cores were uniformly coated by SiO2 and Y2O3:Yb3+,Er3+ layers. The amorphous silica used as the transition layer of UCNPs played an essential role in directing the structure of the composites. The inner Fe3O4 cores and the outer Y2O3:Yb3+,Er3+ layers endow the composites with robust magnetic responsive properties and strong up-conversion fluorescent properties, which endow the nanoparticles with great potential applications in drug targeting, bioseparation and diagnostic analysis.
Co-reporter:Guicun Li;Yingmei Li;Hongrui Peng
Macromolecular Rapid Communications 2011 Volume 32( Issue 15) pp:1195-1199
Publication Date(Web):
DOI:10.1002/marc.201100232
Co-reporter:Xuegang Yu, Yan Shan, Bin Du and Kezheng Chen
CrystEngComm 2011 vol. 13(Issue 5) pp:1525-1530
Publication Date(Web):22 Nov 2010
DOI:10.1039/C0CE00280A
Dendritic and octahedral single-crystal magnetites have been successfully fabricated by a facile one-pot hydrothermal method without any templates. The presented materials were characterized by powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), selection area electron diffraction (SAED) and magnetic property measurement system (MPMS). The results showed that the prepared magnetites with different morphologies have face-centred cubic structures. When using different amounts of potassium hydroxide (KOH) and hydrazine hydrate (N2H4·H2O), high yields of Fe3O4 with well-defined three-dimensional (3D) dendritic and octahedral shapes were obtained. Moreover, the reaction time also has an important effect on the shapes of the products. The crystal growth directions of dendritic and octahedral magnetites are oriented along [110] and [111], respectively. The formation mechanism of the magnetites with different morphologies has been discussed. The magnetic properties are closely related to the morphologies of the magnetites. Furthermore, the as-prepared products have a high saturation magnetization and low coercive force, which endow the materials with great potential for applications in biological fields.
Co-reporter:Yingmei Li, Guicun Li, Hongrui Peng, Kezheng Chen
Materials Letters 2011 Volume 65(Issue 8) pp:1218-1221
Publication Date(Web):30 April 2011
DOI:10.1016/j.matlet.2011.01.059
Self-doped poly(aniline-co-3-aminobenzeneboronic acid) [poly(AN-co-AB)] hollow micro/nanostructures, such as microspheres, aligned pearls, and nanotubes, have been synthesized by one-step chemical oxidation copolymerization of aniline (AN) and 3-aminobenzeneboronic acid (AB) using ammonium peroxydisulfate (APS) as the oxidant in aqueous solution. The process is facile and free of any template, surfactant, and external dopants. The shapes and sizes of poly(AN-co-AB) micro/nanostructures can be controlled by adjusting the synthetic parameters, such as the molar ratios of AN and AB, and the molar ratios of monomer and APS. It is found that both poly(AN-co-AB) hollow microspheres and nanotubes exhibit good electrochemical behavior in neutral solution due to the presence of boronic acid moieties in polyaniline molecular chains.
Co-reporter:Guicun Li, Yingmei Li, Yan Li, Hongrui Peng, and Kezheng Chen
Macromolecules 2011 Volume 44(Issue 23) pp:9319-9323
Publication Date(Web):November 3, 2011
DOI:10.1021/ma2014854
An in situ sacrificial oxidative template route has been developed for the bulk synthesis of two-dimensional polyaniline nanostructures, such as nanorings and flat hollow capsules. In the reaction system, VOPO4·2H2O nanoplates formed spontaneously in V2O5/H2O2/H3PO4 mixture can serve as both oxidant and sacrificial template for the chemical oxidative polymerization of aniline. The synthetic parameters, such as reaction times, the concentrations of H3PO4, and types of the oxidants on the morphologies, sizes, and molecular structures of polyaniline nanostructures have been investigated. The time-dependent experiments reveal that VOPO4·2H2O nanoplate is etched gradually with the polymerization reaction proceeding. The concentration of H3PO4 can adjust the polymerization rate of aniline as well as the etching rate of VOPO4·2H2O, which is critical for controlled synthesis of polyaniline nanorings and flat hollow capsules. The sacrificial oxidative template approach can be extended to synthesize two-dimensional polypyrrole nanostructures.
Co-reporter:Xuegang Yu, Kezheng Chen
Materials Science and Engineering: B 2011 Volume 176(Issue 9) pp:750-755
Publication Date(Web):25 May 2011
DOI:10.1016/j.mseb.2011.02.017
Single-crystalline truncated Fe3O4 cubes with active basal facets have been successfully fabricated through a facile surfactant-free hydrothermal route. The presented materials were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), dynamic light scattering (DLS), selection area electron diffraction (SAED) and magnetic property measurement system (MPMS). The results showed that all products are Fe3O4 with face-center-cubic (FCC) structure. The morphology of Fe3O4 depends on the contents of hydroxide ions, hydrazine hydrate and reaction time. The well-defined truncated Fe3O4 cubes with active basal facets {1 0 0} were fabricated when the pH value, the hydrazine hydrate content and reaction time are 10, 10 mL and 24 h, respectively. The as-prepared Fe3O4 cubes exhibit excellent magnetic properties, which endow the materials with great potential applications in many fields.
Co-reporter:Wei Wang, Min Zou and Kezheng Chen
Chemical Communications 2010 vol. 46(Issue 28) pp:5100-5102
Publication Date(Web):15 Jun 2010
DOI:10.1039/C0CC00262C
Novel Fe3O4@YPO4:Re (Re = Tb, Eu) magnetic–fluorescent hybrid spheres are prepared and present a sustained release behavior for the anticancer drug doxorubicin (DOX) and successful labeling of human cervical carcinoma Hela cells, suggesting promising potential as multifunctional biosensors for biomedical applications.
Co-reporter:Yan Shan, Kezheng Chen, Xuegang Yu, Lian Gao
Applied Surface Science 2010 Volume 257(Issue 2) pp:362-366
Publication Date(Web):1 November 2010
DOI:10.1016/j.apsusc.2010.06.078
Abstract
Magnetic carbon nanotubes consisting of multi-wall carbon nanotubes (MWNTs) core and Fe3O4 shell were successfully prepared by in situ thermal decomposition of Fe(acac)3 or FeCl3 or Fe(CO)5 in 2-pyrrolidone containing acid treated MWNTs at 240 °C with the protection of nitrogen gas. The samples were characterized by TEM, XRD, SEAD, XPS and superconducting quantum interference device. Also, their biocompatibility was compared with naked carbon nanotubes. The results showed that after coated with Fe3O4 nanoparticles, the obtained magnetic carbon nanotubes show superparamagnetic characteristic at room temperature, and their blocking temperature is about 80 K. The magnetic properties of the nanotubes are relevant to the content of magnetic particles, increasing content of magnetic nanoparticles leads to higher blocking temperature and saturation magnetization. The results of antimicrobial activities to bacterial cells (Escherichia coli) showed that the MWNTs have antimicrobial activity, while the magnetic nanotubes are biocompatible even with a higher concentration than that of MWNTs.
Co-reporter:Shuai Zhang, Li Wang, Hongrui Peng, Guicun Li, Kezheng Chen
Materials Chemistry and Physics 2010 Volume 123(2–3) pp:714-718
Publication Date(Web):1 October 2010
DOI:10.1016/j.matchemphys.2010.05.043
LaP1−xVxO4:Tb3+ nanostructures including polyhedral nanocrystals and nanorods, have been synthesized by a facile one-step hydrothermal method in the absence of any surfactant. The influences of synthetic parameters, such as the molar ratios of P and V, and pH values in the reaction system, on the morphologies and crystal structures of LaP1−xVxO4:Tb3+ nanostructures have been investigated. The lattice constants of LaP1−xVxO4:Tb3+ nanostructures are decreased compared with pure LaVO4, and the shapes of LaP1−xVxO4:Tb3+ can be changed from irregular microparticles to polyhedral nanocrystals and nanorods after the introduction of P in to LaVO4 lattice. Photoluminescence spectra show that the photoluminescence properties of LaP1−xVxO4:Tb3+ nanostructures are enhanced strongly with the help of substituting P for V in comparison with the pure LaVO4:Tb3+.
Co-reporter:Shoushan Yu, Jiaqi Wan, Xuegang Yu, Kezheng Chen
Journal of Physics and Chemistry of Solids 2010 Volume 71(Issue 3) pp:412-415
Publication Date(Web):March 2010
DOI:10.1016/j.jpcs.2009.11.011
Superparamagnetic magnetite microspheres with a hydrophobic surface were successfully prepared through a simple solvothermal method based on hydrolysis of iron–oleate complex in diphenyl ether in the presence of oleic acid as the ligands. The microspheres size and size distribution were analyzed by a laser diffraction particle size analyzing method using ZETASIZER. The morphology and crystalline structure of the products were characterized using transmitting electron microscopy (TEM), scanning electron microscopy (SEM), X-Ray diffraction (XRD), and the magnetic property was studied by a Quantum Design MPMS SQUID. TEM and SEM images showed that as-prepared spherical nanostructures are of about 140 nm in sizes, which self-assembled by many 10 nm primary magnetic nanoparticles. The XRD analysis revealed that the magnetic microspheres are composed of magnetite. The magnetic measurements demonstrated that the spherical nanostructures are superparamagnetic at room temperature with no magnetic remanence and coercive force. In addition, the microspheres can be well dispersed in various non-polar solvents due to their surfaces capped of hydrophobic surfactants in situ.
Co-reporter:Guicun Li, Weizhong Wu, Chuanqin Zhang, Hongrui Peng, Kezheng Chen
Materials Letters 2010 Volume 64(Issue 7) pp:820-823
Publication Date(Web):15 April 2010
DOI:10.1016/j.matlet.2010.01.025
Ultra-long single crystalline CuV2O6 nanobelts have been successfully synthesized via a facile homogeneous reaction between peroxovanadic acid and cupric acetate. The reaction parameters, such as reaction time, and with or without H2O2, have profound influences on the crystal structures and morphologies of the resulting products. The time-dependent experiments reveal that the formation of ultra-long CuV2O6 nanobelts is related to the disassembly of urchin-like Cu3(OH)2V2O7·2H2O nanostructures composed of radially aligned nanobelts, and the growth of CuV2O6 along the direction of [010]. Without the addition of H2O2 aqueous solution, wide and short CuV2O6 nanobelts coexist with some irregular particles and microrods in the products.
Co-reporter:Jianwei Wang, Jiaqi Wan, Kezheng Chen
Materials Letters 2010 Volume 64(Issue 21) pp:2373-2375
Publication Date(Web):15 November 2010
DOI:10.1016/j.matlet.2010.07.062
A facile polyol process was established to prepare superparamagnetic Fe-doped ZnO nanoparticles in a liquid polyol using Fe(acac)3 and Zn(acac)2 as precursors and triethylene glycol as the solvent. Scanning electron microscopy (SEM) images showed that as-prepared nanoparticles are uniform in size. X-ray diffraction (XRD) analysis revealed that the nanoparticles are of wurtzite structure without an impure phase. The successful doping of the Fe element into the ZnO host was evident by XRD lines shifting and energy dispersive X-ray spectroscopy (EDS) results. Magnetization measurements demonstrated that the Fe-doped ZnO nanoparticles were superparamagnetic at room temperature.
Co-reporter:Jie Ding, Hongrui Peng, Guicun Li, Kezheng Chen
Materials Letters 2010 Volume 64(Issue 14) pp:1562-1565
Publication Date(Web):31 July 2010
DOI:10.1016/j.matlet.2010.04.038
Orthorhombic V2O5 single-crystalline nanobelts have been synthesized by hydrothermal treating V2O5·xH2O precipitate derived from aqueous solution of V2O5 and H2O2. The synthetic method is facile, fast, environmental friendly, and easy to scale up. The V2O5 single-crystalline nanobelts are 30–80 nm in width, 30–40 nm in thickness, and lengths up to several tens of micrometers. The V2O5·xH2O precursor is crucial for the formation of orthorhombic V2O5 single-crystalline nanobelts. The influences of synthetic parameters, such as reaction time and reaction temperature, on the crystal structures and morphologies of the resulting products have been investigated. Time-dependent experiments show that V2O5·xH2O are dehydrated gradually and converted into orthorhombic V2O5 single-crystalline nanobelts. High reaction temperature also favors the formation of orthorhombic V2O5 nanobelts.
Co-reporter:Li Wang ; Kezheng Chen ;Lifeng Dong
The Journal of Physical Chemistry C 2010 Volume 114(Issue 41) pp:17358-17361
Publication Date(Web):September 28, 2010
DOI:10.1021/jp104706q
ZnO nanoribbons with zigzag edges and ultrafine nanowire-like tips (diameter about 10 nm) were synthesized via a facile method at a relatively low temperature without any catalysts or templates. The nanoribbons are about 30 nm in thickness, 500 nm in length, and tapered in width. It is hydrogen peroxide that results in the formation of ZnO nanoribbons with zigzag edges. As an oxidant, hydrogen peroxide provides not only oxygen for the growth of ZnO nanoribbons but also water vapor for impeding the growth of the nanoribbons along [0001] and accelerating the <011̅0> growth of ZnO nanoribbons. Bottom-gate ZnO-nanoribbon-based field-effect transistors demonstrated n-type field-effect conduction, and the current on-to-off ratio was as high as 1 × 104. The novel method developed in this study can be used to synthesize other metal oxides with zigzag edges.
Co-reporter:Guicun Li, Chuanqin Zhang, Yingmei Li, Hongrui Peng, Kezheng Chen
Polymer 2010 Volume 51(Issue 9) pp:1934-1939
Publication Date(Web):20 April 2010
DOI:10.1016/j.polymer.2010.03.004
High quality polyaniline nanofibers have been synthesized by a rapid polymerization of aniline using ammonium peroxydisulfate (APS)/Fe2+ redox initiator as the oxidant without any hard or soft templates. The addition of Fe2+ in conventional polymerization system plays an important role in changing the bulk morphologies of polyaniline from irregular particle agglomerates to nanofibers. Open-circuit potential measurements indicate that the rate of polymerization of aniline with the aid of Fe2+ ions has a substantial increase. The influences of synthetic parameters, such as the concentrations of aniline, dopant, and redox initiator, and reaction time, on the sizes and morphologies of polyaniline nanostructures have been investigated for elucidating the formation of polyaniline nanofibers. Fourier transform infrared spectrum, UV–vis spectrum, and cyclic voltammograms reveal that the molecular structures and electrochemical properties of polyaniline nanofibers do not differ significantly from that of conventional polyaniline.
Co-reporter:Xuegang Yu, Jiaqi Wan, Yan Shan, Kezheng Chen and Xiaodong Han
Chemistry of Materials 2009 Volume 21(Issue 20) pp:4892
Publication Date(Web):September 28, 2009
DOI:10.1021/cm902667b
Bifunctional magnetic-optical Fe3O4@ZnS microspheres with core−shell heterostructures have been successfully fabricated by a simple chemical deposition method. The adsorption of sodium dodecyl sulfate (SDS) on the preformed magnetite microspheres played an essential role in directing the structure of the composites. The presented materials were characterized by FE-SEM, HRTEM, XRD, FTIR, fluorescence spectrophotometer, and SQUID MPMS. The results showed that spherical Fe3O4 cores were coated by a uniform ZnS layer. The saturation magnetization value of Fe3O4@ZnS core−shell microspheres is 52.5 emu g−1 at room temperature. Ultraviolet and visible light can be easily obtained by exposing the microspheres to different excitation wavelengths. The combined magnetic and fluorescent properties endow the microspheres with great potential applications in drug targeting, bioseparation and diagnostic analysis.
Co-reporter:Guicun Li;Chuanqin Zhang;Hongrui Peng
Macromolecular Rapid Communications 2009 Volume 30( Issue 21) pp:1841-1845
Publication Date(Web):
DOI:10.1002/marc.200900322
Co-reporter:Jiaqi Wan, Hui Li, Kezheng Chen
Materials Chemistry and Physics 2009 Volume 114(Issue 1) pp:30-32
Publication Date(Web):15 March 2009
DOI:10.1016/j.matchemphys.2008.10.039
Fe3O4@ZnO core–shell structured nanoparticles have been synthesized by a simple one-pot sequential polyol process. The nanoparticles have been investigated by powder X-ray diffraction (XRD), transmission electron microscope (TEM), energy-dispersive X-ray spectrometer (EDS) and physical properties measurement system (PPMS) of Quantum Design.
Co-reporter:Chuanqin Zhang;Li Wang;Hongrui Peng;Guicun Li
Polymer International 2009 Volume 58( Issue 12) pp:1422-1426
Publication Date(Web):
DOI:10.1002/pi.2677
Abstract
BACKGROUND: Polyaniline–vanadium oxide hybrid materials have been much researched due to their potential applications in lithium batteries. Although many methods have been reported for the fabrication of conventional polyaniline–vanadium oxide hybrid materials by in situ oxidative polymerization/intercalation of aniline in V2O5 and by layer-by-layer approaches, studies on polyaniline–vanadium oxide hybrid nanostructures have been rare.
RESULTS: Polyaniline–vanadium oxide hybrid hierarchical architectures assembled from nanoscale building blocks, such as nanoplates and nanobelts, have been synthesized by a one-step hydrothermal homogeneous reaction between aniline and peroxovanadic acid without the aid of any surfactant or template. The influences of synthesis parameters, i.e. reaction time, temperature and medium, on the morphologies of the polyaniline–vanadium oxide hybrid nanostructures have been investigated. With increasing reaction time/temperature, the alignment of nanoplates in the hierarchical architectures becomes gradually dense.
CONCLUSION: The formation mechanism of the polyaniline–vanadium oxide hybrid hierarchical architectures involves a one-step precipitation–polymerization–assembly process. The method may be applicable for the synthesis of other conducting polymer–vanadium oxide hybrid nanostructures. Copyright © 2009 Society of Chemical Industry
Co-reporter:Chongju Liu, Yan Shan, Yanlou Zhu, Kezheng Chen
Thin Solid Films 2009 Volume 518(Issue 1) pp:324-327
Publication Date(Web):2 November 2009
DOI:10.1016/j.tsf.2009.07.052
The fabrication of monolayer film of surfactant-stabilized magnetic Fe3O4 particles with a size range of 90–150 nm via the Langmuir-Blodgett method is described in this paper. Magnetic Fe3O4 particles coated with oleic acid were firstly synthesized by a hydrothermal process, and then the particles were dispersed into chloroform. After that, the Fe3O4 suspension was spread to the interface of air/water and transferred to the glass surface. The formation of the Langmuir monolayer of oleic acid-stabilized Fe3O4 particles at air/water interface was revealed with the pressure-area isotherm curves. The results of the surface pressure-area isotherm and Atomic Force Microscopy showed that this film is a well compressed monolayer of 2-dimensional Fe3O4 particles assembly. Magnetometry results showed that the saturation magnetization of Fe3O4 magnetic particles is 86.1 A·m2/kg at room temperature with an applied field of 0.6 T.
Co-reporter:Ruixue Sun, Kezheng Chen, Yupeng Lu
Materials Research Bulletin 2009 44(10) pp: 1939-1942
Publication Date(Web):
DOI:10.1016/j.materresbull.2009.06.015
Co-reporter:Ruipeng Fu, Wei Wang, Rongjiang Han, Kezheng Chen
Materials Letters 2008 Volume 62(Issue 25) pp:4066-4068
Publication Date(Web):30 September 2008
DOI:10.1016/j.matlet.2008.05.006
γ-Fe2O3/ZnO composite particles were prepared via a simple solution method using surface-modified γ-Fe2O3 nanoparticles as seeds. The phases and purity of the as-prepared γ-Fe2O3/ZnO composite particles were characterized by XRD analysis, and the morphology was studied by SEM, which showed that the γ-Fe2O3/ZnO composites are of typical sphere-like morphology with diameters in the range of 300–400 nm. The γ-Fe2O3/ZnO composites exhibit magnetic response to an external magnet field and efficient characteristic emissions of ZnO under UV excitation, respectively, indicating that these nontoxic, emissive and magnetic nanoparticles may find use as chemical/biological sensors especially in areas that directly impact human health.
Co-reporter:Kezheng Chen, A.F. Bakuzis, Weili Luo
Applied Surface Science 2006 Volume 252(Issue 18) pp:6379-6382
Publication Date(Web):15 July 2006
DOI:10.1016/j.apsusc.2005.12.160
Abstract
The grafting number of surfactant coating on magnetite nanoparticles in a magnetic colloid (magnetic fluid), defined as the number of surfactant molecules adsorbed per surface area of nanoparticles, was successfully obtained from the atomic absorption spectroscopy and transmission electron microscopy. We found that the increases of grafting number with the molar concentration of surfactant and the adsorption temperature can be quantitatively measured, making it possible to produce well controlled, stable magnetic colloids that are precursors for many magnetic nanostructures.
Co-reporter:Yongchao Bao, Kezheng Chen
Molecular Catalysis (May 2017) Volume 432() pp:187-195
Publication Date(Web):1 May 2017
DOI:10.1016/j.mcat.2017.01.008
•Novel Z-scheme visible light driven Cu2O/Cu/g-C3N4 photocatalysts were successfully prepared via one step reduction method.•Cu2O/Cu/g-C3N4 displays enhanced photocatalytic activity than g-C3N4, Cu/Cu2O Cu/g-C3N4 and Cu2O/g-C3N4.•Metallic Cu particles act as a charge transfer mediator.The novel Cu2O/Cu/g-C3N4 composites were successfully synthesized via one step reduction method in the presence of g-C3N4. Under visible light irradiation, the Cu2O/Cu/g-C3N4 composites exhibited higher photocatalytic activity than g-C3N4 and Cu/Cu2O, and the 20 at% Cu2O/Cu/g-C3N4 photocatalyst displayed the highest photocatalytic activity. The enhanced photcatalytic mechanism was investigated by radical-trapping and electron spin resonance experiments. A Z-scheme charge transfer mechanism was proposed, in which metallic Cu particles acted as charge separation center. This work could provide some insight into the design of novel Z-scheme photocatalyst with metallic Cu particles as a charge transfer mediator.Download full-size image
Co-reporter:Ji Ma, Shuangshuang Sun, Kezheng Chen
Bioresource Technology (June 2017) Volume 233() pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.biortech.2017.02.075
•Magnetic adsorbents were synthesized via a soak-calcination method using fruit peels.•These adsorbents feature the merits of appropriate ferromagnetism (>4 emu g−1).•These adsorbents exhibit high adsorption capacity for dyes and Cr6+ ions.In this study, apple, banana and orange peels were used as precursor compounds for the mass production of magnetite/carbon adsorbents. A so-called “soak-calcination” procedure was employed by firstly soaking these waste fruit peels in FeCl3 aqueous solutions and secondly calcining these precursors in the nitrogen atmosphere to yield final magnetite/carbon composites. This approach is quite simple and effective to synthesize carbon-based adsorbents on an industrial scale. The as-produced adsorbents feature the merits of appropriate ferromagnetism (>4 emu g−1), high adsorption capacity (several hundreds of milligrams per gram for adsorption of methyl blue, Congo red, rhodamine B and Cr6+ ions), and good regenerability (>85%).
Co-reporter:Wei Liu, Ji Ma, Shuangshuang Sun, Kezheng Chen
Journal of Water Process Engineering (August 2016) Volume 12() pp:111-119
Publication Date(Web):1 August 2016
DOI:10.1016/j.jwpe.2016.07.003
•Porous Fe@SiO2 hierarchical capsules were prepared by a two-step solution method.•The maximum Cr (VI) adsorption capacity of Fe@SiO2 capsules was ca. 1400 mg g−1.•The initial Cr (VI) adsorption rate of Fe@SiO2 capsules was ca. 19 mg g−1 min−1.•The Fe@SiO2 capsules can rapidly respond to an external magnetic field.In this work, porous Fe@SiO2 hierarchical microcapsules were fabricated by reducing α-Fe2O3@SiO2 micro-spindles, which were prepared by using a two-step solution method. These Fe@SiO2 microcapsules were then employed to remove Cr (VI) ion from water. On the basis of Langmuir isotherms model, the maximum Cr (VI) adsorption capacities were estimated to be ca. 1400 and 1300 mg g−1 at 305 and 310 K, respectively. These values, to our knowledge, were much higher than those in previous reports for many other Fe-based adsorbents. Besides, the initial Cr (VI) adsorption rate was calculated to be ca. 19 mg g−1 min−1 that was significantly higher than those reported in previous literatures, and hence improving the adsorptive efficiency of Fe@SiO2 microcapsules in practical water treatment. Thermodynamic analyses of enthalpy, entropy and Gibbs free energy further evidenced that these outstanding kinetics and equilibrium results were mainly due to a physical adsorption process, accompanied by a chemisorption associated with the reduction of Cr (VI) to Cr (III). The gram-grade Cr (VI) adsorption capacities and easy magnetic separation are highly desirable for their widespread potential applications in water treatment.
Co-reporter:Guicun Li, Shuai Zhang, Hongrui Peng, Kezheng Chen
Journal of Crystal Growth (1 October 2010) Volume 312(Issue 20) pp:2967-2971
Publication Date(Web):1 October 2010
DOI:10.1016/j.jcrysgro.2010.07.025
Orthorhombic Fe5(PO4)4(OH)3·2H2O single crystalline dendritic nanostructures have been synthesized by a facile and reproducible hydrothermal method without the aid of any surfactants. The influences of synthetic parameters, such as reaction time, temperature, the amount of H2O2 solution, pH values, and types of iron precursors, on the crystal structures and morphologies of the resulting products have been investigated. The formation process of Fe5(PO4)4(OH)3·2H2O dendritic nanostructures is time dependent: amorphous FePO4·nH2O nanoparticles are formed firstly, and then Fe5(PO4)4(OH)3·2H2O dendrites are assembled via a crystallization-orientation attachment process, accompanying a color change from yellow to green. The shapes and sizes of Fe5(PO4)4(OH)3·2H2O products can be controlled by adjusting the amount of H2O2 solution, pH values, and types of iron precursors in the reaction system.
Co-reporter:Baolong Zhang, Yan Shan, Kezheng Chen
Materials Chemistry and Physics (1 June 2017) Volume 193() pp:82-88
Publication Date(Web):1 June 2017
DOI:10.1016/j.matchemphys.2017.01.079
Co-reporter:Yichao Yin, Chenjie Liu, Baoxiang Wang, Shoushan Yu and Kezheng Chen
Dalton Transactions 2013 - vol. 42(Issue 19) pp:NaN7240-7240
Publication Date(Web):2013/03/07
DOI:10.1039/C3DT32559H
A simple, one-pot solvothermal method has been demonstrated for the preparation of bifunctional Fe3O4@titanium oxide core/shell nanoparticles. In a typical procedure, tetraalkoxyl titanium Ti(OC4H9)4 and FeCl3 as precursors were added into ethylene glycol and further solvothermal treatment was used to synthesize the core/shell particles. The core/shell particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), SQUID MPMS and rheometry. The morphological results showed titanium oxide nanorods with 100–200 nm length and 10–20 nm diameter coated on the surface of 200–300 nm Fe3O4 submicrospheres. Reaction time, the titanium source, the barium salt etc. have an influence on the morphology of core/shell particles. The core/shell particles can not only respond to an external magnetic field, but also to an electric field – a novel application of electrorheological fluid.
Co-reporter:Yong Wang, Ji Ma and Kezheng Chen
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 44) pp:NaN19421-19421
Publication Date(Web):2013/10/01
DOI:10.1039/C3CP52867G
A novel hollow urchin-like α-FeOOH hierarchical structure was fabricated via a one-pot hydrothermal procedure without using any templates, surfactants or organic raw materials. An inside-out amorphous ripening mechanism was proposed to unravel its structural evolution. The kinetics, equilibrium and thermodynamics of its adsorptive removal of Cr(VI) from wastewater were comprehensively investigated. It was found that the adsorption process can be depicted using a pseudo-second-order model, and a high adsorption capacity of 58.97 mg g−1 was obtained from the equilibrium adsorption isotherm. Also, the thermodynamic parameters (i.e., enthalpy, entropy and Gibbs free energy) at different temperatures were acquired to reveal a spontaneous adsorption process, with both physical and chemical characteristics.
Co-reporter:Wei Wang, Xiangpeng Jiang and Kezheng Chen
Dalton Transactions 2012 - vol. 41(Issue 2) pp:NaN497-497
Publication Date(Web):2011/10/31
DOI:10.1039/C1DT11200G
Lanthanide-doped chitosan nanospheres (LDCNs) and lanthanide-Fe3O4-doped chitosan nanospheres (Fe3O4-LDCNs) are fabricated and show fluorescence, MRI effectiveness and desirable biocompatibility. Superior to most nanoparticles that were found retained in cytoplasmic organelles rather than the nucleus, the prepared chitosan nanospheres preferentially enter and illuminate the cell nuclei. Complexation of plasmid DNA (pDNA) to the nanospheres was accomplished via electrostatic forces between positively charged chitosan and negatively charged pDNA. Satisfactory results of the complexation indicate that the prepared chitosan nanospheres can serve as a potential fluorescent nonviral vector for pDNA delivery that can fulfill gene delivery and transfer efficiency assessment simultaneously, without an additional step of tagging fluorophores to the vectors carried out in fabrications of currently available pDNA delivery vectors.
Co-reporter:Jiaqi Wan, Xuehui Jiang, Hui Li and Kezheng Chen
Journal of Materials Chemistry A 2012 - vol. 22(Issue 27) pp:NaN13505-13505
Publication Date(Web):2012/05/09
DOI:10.1039/C2JM30684K
Monodisperse ZnFe2O4 nanoparticles were synthesized using a simple and low-cost polyol process based on thermal decomposition of the precursors of Fe(acac)3 and Zn(acac)2 in triethylene glycol without any surfactant. The as-prepared ZnFe2O4 nanoparticles are highly crystalline, uniform in size, superparamagnetic and can be easily dispersed in aqueous media due to being coated by a layer of hydrophilic polyol ligands in situ. Magnetic study shown that the ZnFe2O4 nanoparticles had a low magnetic anisotropy and low magnetic moment compared to the conventional Fe3O4 nanoparticles. As a result, the as-prepared ZnFe2O4 nanoparticles provide an optimized r2/r1 ratio for T1-weighted magnetic resonance imaging (MRI) in the clinical field strength. A preliminary in vitro cytotoxicity test suggests that the zinc ferrite nanoparticles possess a good safety profile. Therefore, the as-prepared ZnFe2O4 nanoparticles have great potential to serve as a novel non-lanthanide T1 MRI contrast agent.
Co-reporter:Zhonghua Zhang, Guicun Li, Hongrui Peng and Kezheng Chen
Journal of Materials Chemistry A 2013 - vol. 1(Issue 48) pp:NaN15434-15434
Publication Date(Web):2013/10/22
DOI:10.1039/C3TA13860G
Hierarchical hollow microspheres composed of N-doped carbon coated Li4Ti5O12 nanosheets (NC-LTO) have been synthesized on a large scale by a facile low-temperature solution-based approach combined with high temperature calcination. The primary Li4Ti5O12 nanosheets show zigzag morphology with a typical thickness of about 5.0 nm, which are uniformly coated with N-doped carbon layers. When evaluated for lithium storage capacity, the NC-LTO hollow microspheres display enhanced electrochemical energy storage performances compared to the pristine hollow microspheres composed of Li4Ti5O12 nanosheets (A-LTO), including high capacity (181.4 mA h g−1 at 0.5 C), excellent rate capability (140.8 mA h g−1 at 20 C), and good cyclic stability (92.8% capacity loss after 100 cycles at 20 C). The reasons for these improvements are explored in terms of the increased electronic conductivity and the facilitation of lithium ion transport arising from the introduction of N-doped carbon layers and the thin zigzag Li4Ti5O12 nanosheets.
Co-reporter:Xuegang Yu, Yan Shan, Guicun Li and Kezheng Chen
Journal of Materials Chemistry A 2011 - vol. 21(Issue 22) pp:NaN8109-8109
Publication Date(Web):2011/04/28
DOI:10.1039/C1JM10622H
Bifunctional magnetic–optical Fe3O4@SiO2@Y2O3:Yb3+,Er3+ near-infrared-to-visible up-conversion nanoparticles (UCNPs) with core–shell structures have been successfully fabricated by a facile layer-by-layer method. The presented materials were characterized by XRD, FTIR, TEM, fluorescence spectrophotometer, NMR Analyzer and SQUID MPMS. The results showed that the Fe3O4 cores were uniformly coated by SiO2 and Y2O3:Yb3+,Er3+ layers. The amorphous silica used as the transition layer of UCNPs played an essential role in directing the structure of the composites. The inner Fe3O4 cores and the outer Y2O3:Yb3+,Er3+ layers endow the composites with robust magnetic responsive properties and strong up-conversion fluorescent properties, which endow the nanoparticles with great potential applications in drug targeting, bioseparation and diagnostic analysis.
Co-reporter:Hao Li, Shaoxin Song, Wei Wang and Kezheng Chen
Dalton Transactions 2015 - vol. 44(Issue 36) pp:NaN16090-16090
Publication Date(Web):2015/08/05
DOI:10.1039/C5DT01015B
Yb3+ and Er3+ co-doped Gd2O3 nanoparticles were synthesized via a simple homogeneous precipitation method followed by subsequent heat treatment. Morphology characterization results showed that these nanoparticles were almost spherical in shape with diameters of 200–400 nm. The particles were further modified by polyethylene glycol (PEG) to improve their suspensibility in water. The sintering temperature was found to greatly influence the fluorescent properties of the products. After calcination at 700–1200 °C, the Gd2O3:Yb,Er nanoparticles could emit bright up-conversion fluorescence under 980 nm near-infrared (NIR) laser light excitation. The mechanism of up-conversion fluorescence was studied in detail and a three-photon process was observed for both green and red up-conversion fluorescence of the Gd2O3:Yb,Er nanoparticles. Different from many other Yb3+,Er3+ co-doped up-conversion materials, the prepared Gd2O3:Yb,Er nanoparticles emitted much stronger red light than green light. The reason was investigated and ascribed to the presence of abundant hydroxyl groups on the surface of the nanoparticles as a result of PEGylation. The nanoparticles could be taken up by the human cervical cancer (HeLa) cells and presented low toxicity. Well-selected photodynamic therapy (PDT) drugs, methylene blue (MB) with a UV/Vis absorption maximum (λmax) of 665 nm and 5-aminolevulinic acid (5ALA) which is a precursor of the natural photosensitizer photoporphyrin IX (PpIX) with a λmax of 635 nm, were loaded onto the nanoparticles respectively to obtain Gd2O3:Yb,Er-MB and Gd2O3:Yb,Er-5ALA nanoparticles. Being up-conversion nanoparticles (UCNPs), the taken up Gd2O3:Yb,Er nanoparticles exposed to 980 nm laser light emitted red fluorescence which activated the loaded MB and PpIX, and then killed the HeLa cells via a PDT mechanism. In vitro therapeutic investigation evidenced the prominent PDT effects of Gd2O3:Yb,Er-MB and Gd2O3:Yb,Er-5ALA upon NIR light irradiation. In magnetic resonance imaging (MRI) studies, the relaxivity values obtained for Gd2O3:Yb,Er were r1 = 2.2705 M−1 s−1 and r2 = 3.0675 M−1 s−1 with a r2/r1 ratio close to 1, suggesting that it would be a good candidate as a positive MRI agent. It is expected that these particles have applications in magnetic-fluorescent bimodal imaging and NIR light-triggered PDT.
Co-reporter:Jiaqi Wan, Jing Tang, Chongyu Zhang, Ruiting Yuan and Kezheng Chen
Chemical Communications 2015 - vol. 51(Issue 88) pp:NaN15913-15913
Publication Date(Web):2015/07/21
DOI:10.1039/C5CC03685B
Uniform magnetite mesocrystals were fabricated by solvothermal treatment of ferrous chloride in ethylene glycol in the presence of sodium hydroxide. The formation mechanism of magnetite mesocrystals in ethylene glycol was deduced by a time-dependent experiment.
Co-reporter:Baoxiang Wang, Yichao Yin, Chenjie Liu, Shoushan Yu and Kezheng Chen
Dalton Transactions 2013 - vol. 42(Issue 27) pp:NaN10055-10055
Publication Date(Web):2013/04/30
DOI:10.1039/C3DT50504A
Flower-like BaTiO3/Fe3O4 hierarchically structured particles composed of nano-scale structures on micro-scale materials were synthesized by a simple solvothermal approach and characterized by the means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), magnetic testing and rotary viscometer. The influences on the morphology and structure of solvothermal times, type and amount of surfactant, EG:H2O ratio, etc. were studied. Magnetic testing results show that the samples have strong magnetism and they exhibit superparamagnetic behavior, as evidenced by no coercivity and the remanence at room temperature, due to their very small sizes, observed on the M–H loop. The saturation magnetization (Ms) value can achieve 18.3 emu g−1. The electrorheological (ER) effect was investigated using a suspension of the flower-like BaTiO3/Fe3O4 hierarchically structured particles dispersed in silicone oil. We can observe a slight shear-thinning behavior of shear viscosity at a low shear rate region even at zero applied electric field and a Newtonian fluid behavior at high shear rate regions.
Co-reporter:Ji Ma, Xiaodan Zhang, Kezheng Chen, Guicun Li and Xiaodong Han
Journal of Materials Chemistry A 2013 - vol. 1(Issue 18) pp:NaN5553-5553
Publication Date(Web):2013/02/28
DOI:10.1039/C3TA10396J
A series of hematite hierarchical structures, including amorphous hierarchical spheres with varied internal polycrystalline structures, single-crystalline nanoflakes and co-aligned micro-layered structures, have been fabricated by simply controlling the reaction time in a one-step hydrothermal procedure. In the early stages of the reaction, an Ostwald ripening process dominates the successive occurrence of single-shell, double-shell and yolk–shell spheres, which reoccur in reverse order under the effect of an H+ etching process on prolonging the reaction time. Afterwards, the oriented attachment mechanism takes charge of the formation of single-crystalline nanoflakes and co-aligned micro-layered structures at the expense of the previously formed spheres. It is found that the different adsorption configuration of the hydroxyl groups in different crystallographic planes is of fundamental importance to the morphology evolution from nanoflakes to micro-layered structures. The electrochemical measurements of these hierarchical structures show that their lithium storage properties are closely related to their crystallinity and morphology. The amorphous-based architectures exhibit quite similar electrochemical properties regardless of their morphologies, whereas the crystallized architectures present morphology-dependent electrochemical properties. Also, well-crystallized electrodes facilitate the access of lithium-ions and thus possess superior lithium storage performances, whether in the initial charge–discharge cycling or in the subsequent cyclic capacity retention.
Co-reporter:Xiaojun Wei, Wei Wang and Kezheng Chen
Dalton Transactions 2013 - vol. 42(Issue 5) pp:NaN1759-1759
Publication Date(Web):2012/10/29
DOI:10.1039/C2DT31783D
As bimodal magnetic-fluorescent imaging agents, the preparation of ZnS:Tb,Gd and ZnS:Er,Yb,Gd nanoparticles via a facile homogeneous precipitation method is reported. The results show that these nanoparticles are almost spherical in shape with a diameter of 100–200 nm approximately and a major phase of wurtzite-structured ZnS. The products can successfully label the human hepatocellular carcinoma (HepG2) cells and present low toxicity even at concentrations up to 5 mg mL−1. Additionally, for the ZnS:Er,Yb,Gd nanoparticles calcinated above 950 °C, NIR-to-visible up-conversion fluorescence were obtained, which is believed to be superior to traditional ZnS-based bioimaging agents with down conversion. In MRI studies, they reveal a longitudinal relaxivity rate (r1) of 39.46 mM−1 s−1 and 57.8 mM−1 s−1, respectively, which are much larger than the conventional Gd-DTPA and currently reported Gd-base nanoparticles, suggesting great potential as MRI agents.
Co-reporter:Wei Wang, Min Zou and Kezheng Chen
Chemical Communications 2010 - vol. 46(Issue 28) pp:NaN5102-5102
Publication Date(Web):2010/06/15
DOI:10.1039/C0CC00262C
Novel Fe3O4@YPO4:Re (Re = Tb, Eu) magnetic–fluorescent hybrid spheres are prepared and present a sustained release behavior for the anticancer drug doxorubicin (DOX) and successful labeling of human cervical carcinoma Hela cells, suggesting promising potential as multifunctional biosensors for biomedical applications.
Co-reporter:Wei Wang, Xiangpeng Jiang and Kezheng Chen
Chemical Communications 2012 - vol. 48(Issue 58) pp:NaN7291-7291
Publication Date(Web):2012/05/23
DOI:10.1039/C2CC32429F
Novel iron phosphates microflowers which show SOD-like and peroxidase-like mimic activities were prepared, suggesting potential applications as a biocatalyst and a biosensor for H2O2.
Co-reporter:Wei Wang, Xiangpeng Jiang and Kezheng Chen
Chemical Communications 2012 - vol. 48(Issue 54) pp:NaN6841-6841
Publication Date(Web):2012/05/16
DOI:10.1039/C2CC32328A
Solvothermally synthesized CePO4:Tb,Gd hollow nanospheres were fabricated as a peroxidase mimic and bimodal magnetic–fluorescent imaging agent, which show potential applications in biocatalysis and bioimaging.
