石墨烯-Fe@Fe_3O_4纳米复合材料的制备及其电磁性能研究

采用改进Hummers法制备氧化石墨,通过高温热膨胀剥离氧化石墨获得多层石墨烯,最后由羰基铁热分解法原位制备多层石墨烯-Fe@Fe3O4纳米复合材料。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、振动样品磁强计(VSM)以及矢量网络分析仪等对该复合材料的结构、形貌、电磁参数等进行了表征和测试。结果表明,石墨烯片层上附着了尺寸小于50 nm的球形Fe@Fe3O4颗粒;反射率损耗(RL)计算结果表明:以金属为衬底,当复合材料厚度为1.5 mm时,在10～16GHz范围内反射损耗均在-10 dB以下;当厚度为3 mm时,材料的反射损耗在4.3 GHz处达最大值,约为-25 dB。

Folate-conjugated Fe_3O_4 nanoparticles for in vivo tumor labeling

Highly biocompatible superparamagnetic Fe3O4 nanoparticles were synthesized by amide of folic acid （FA） ligands and the NH2-group onto the surface of Fe3O4 nanoparticles. The as-synthesized folate-conjugated Fe3O4 nanoparticles were characterized by X-ray diffraction diffractometer, transmission electron microscope, FT-IR spectrometer, vibrating sample magnetometer, and dynamic light scattering instrument. The in vivo labeling effect of folate-conjugated Fe3O4 nanoparticles on the hepatoma cells was investigated in tumor-bearing rat. The results demonstrate that the as-prepared nanoparticles have cubic structure of Fe3O4 with a particle size of about 8 nm and hydrated diameter of 25.7 nm at a saturation magnetization of 51 A·m2/kg. These nanoparticles possess good physiological stability, low cytotoxicity on human skin fibroblasts and negligible effect on Wistar rats at the concentration as high as 3 mg/kg body mass. The folate-conjugated Fe3O4 nanoparticles could be effectively mediated into the human hepatoma Bel 7402 cells through the binding of folate and folic acid receptor, enhancing the signal contrast of tumor tissue and surrounding normal tissue in MRI imaging. It is in favor of the tumor cells labeling, tracing, magnetic resonance imaging （MRI） target detection and magnetic hyperthermia.

Fe3O4NPs对模拟大豆蛋白废水厌氧产甲烷的影响及动力学分析

为了提升大豆蛋白废水厌氧发酵产气性能,通过批式实验探究纳米Fe3O4(Fe3O4nanoparticles,Fe3O4NPs)对模拟大豆蛋白废水厌氧发酵产甲烷的影响,并采用2种不同模型对发酵过程中累积甲烷产量进行动力学分析。结果表明,添加适量的Fe3O4NPs有助于提高大豆蛋白废水厌氧发酵产气量和有机物去除率,促进产甲烷过程。质量浓度为300 mg/L时,累积产气量达到652.12 m L,比对照组提高23.51%,平均甲烷含量为81.63%;可溶性化学需氧量(soluble chemical oxygen demand,SCOD)、生化需氧量(biochemical oxygen demand,BOD5)和蛋白质去除率均最高,分别为89.11%、91.91%和71.52%,甲烷产率达到331.40 m L/g SCOD;添加Fe3O4NPs可以降低厌氧发酵过程中氨氮和总氮浓度。Transference模型和改进的Gompertz模型均可较好地拟合大豆蛋白废水厌氧发酵产甲烷过程,前者拟合度更高(R2>0.96),且Fe3O4NPs质量浓度为300 mg/L时获得的最大甲烷产率为350.84 m L/g SCOD。

Fe@Fe_2O_3/g-C_3N_4复合光催化剂的制备及其性能

通过高温煅烧三聚氰胺制备了石墨相氮化碳g-C_3N_4,再以硼氢化钠(NaBH_4)为还原剂,室温下还原氯化高铁(FeCl_3·6H_2O)制备出了具有核壳结构的Fe@Fe_2O_3纳米线。然后分别通过超声法和溶剂热法制备了Fe@Fe_2O_3/g-C_3N_4复合光催化剂,并利用X-射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等表征方法对其进行表征。所得样品的光催化性能通过在可见光下(λ≥400 nm)光催化降解罗丹明B(RhB)溶液来评估。研究表明,超声法制备的Fe@Fe_2O_3/g-C_3N_4复合催化剂具有优良的可见光催化性能,其催化活性明显高于单组分的催化活性,一般认为Fe@Fe_2O_3与g-C_3N_4之间有一定的协同作用,从而可以提高材料的催化活性。同时,研究发现该催化体系中起关键作用的主要活性物种是超氧自由基。

磁性Fe_3O_4-CeO_2 NPs/GO的制备及其高效去除氮氧化物的研究

本课题设计合成了磁性Fe3O_4-CeO_2NPs/GO纳米复合材料,通过催化H_2O_2产生氧自由基,将NO转化为硝酸。试验结果证明,NO_x的处理效率可达96. 0%以上。本课题实现了氮氧化物的资源化治理,"变废为宝",并利用复合材料的磁性实现对催化剂的简易回收和循环使用。具有广阔的应用前景和推广价值。

Size-dependent peroxidase-like catalytic activity of Fe_3O_4 nanoparticles

Peroxidase-like catalytic properties of Fe3O4 nanoparficles （NPs） with three different sizes, synthesized by chemical coprecipitation and sol-gel methods, were investigated by UV-vis spectrum analysis. By comparing Fe3O4 NPs with average diameters of 11, 20, and 150 nm, we found that the catalytic activity increases with the reduced nanoparticle size. The electrochemical method to characterize the catalytic activity of Fe3O4 NPs using the response currents of the reaction product and substrate was also developed.

Surface organic modification of Fe_3O_4 nanoparticles by silane-coupling agents

Fe3O4 nanoparticles were prepared by chemistry co-precipitation and the mean crystal size was 17.9 nm measured by XRD. After it had been treated by silane-coupling agents KH570, magnetic micro-spheres dispersed in organic medium glycol were gained and the mean size of Fe3O4 nanopowders was 33.7 nm. So it can be concluded that magnetic micro-sphere is made of a few Fe3O4 crystals. Many factors of modification were researched, such as the time of ball milling, the content of Fe3O4 and the content of KH570. The modification of Fe3O4 is relative to the time of ball milling, but the dominant function is affected by the content of Fe3O4 and KH570. When the content of Fe3O4 is known, there is a suitable content of KH570. Different content of Fe3O4 will make the different suitable content of KH570, but the range of latter is less than former, which is relative to the distribution of KH570 on Fe3O4 surface or in the solution.

Surface Organic Modification of Fe_3O_4 Magnetic Nanoparticles

The surface organic modification of Fe3O4 nanoparticles with silane coupling reagent KH570 was studied. The modified and unmodified nanoparticles were characterized by FT-IR, XPS and TEM. The spectra of FT-IR and XPS revealed that KH570 was coated onto the surface of Fe3O4 nanoparticles to get Fe-O- Si bond and an organic coating layer also was formed. Fe3O4 nanoparticles were spheres partly with mean size of 18,8 nm studied by TEM, which was consistent with the result 17.9 nm calculated by Scherrer＇s equation. KH570 was adsorbed on surface and formed chemistry bond to be steric hindrance repulsion which prevented nanoparticles from reuniting. Then glycol-based Fe3O4 magnetic liquids dispersed stably was gained.

Novel Co_3O_4 Nanoparticles/Nitrogen-Doped Carbon Composites with Extraordinary Catalytic Activity for Oxygen Evolution Reaction(OER)

Herein, Co_3O_4 nanoparticles/nitrogen-doped carbon(Co_3O_4/NPC) composites with different structures were prepared via a facile method. Structure control was achieved by the rational morphology design of ZIF-67 precursors, which were then pyrolyzed in air to obtain Co_3O_4/NPC composites. When applied as catalysts for the oxygen evolution reaction(OER), the M-Co_3O_4/NPC composites derived from the flower-like ZIF-67 showedsuperior catalytic activities than those derived from the rhombic dodecahedron and hollow spherical ZIF-67. The former M-Co_3O_4/NPC composite displayed a small overpotential of 0.3 V, low onset potential of 1.41 V, small Tafel slope of 83 m V dec^(-1), and a desirable stability.(94.7% OER activity was retained after 10 h.) The excellent performance of the flower-like M-Co_3O_4/NPC composite in the OER was attributed to its favorable structure.

Fe3O4 nanoparticles impregnated eggshell as a novel catalyst for enhanced biodiesel production

Biodiesel is a green fuel which can replace diesel while addressing various issues such as scarcity of hydrocarbon fuels and environmental pollution to an extent. The high production cost of biodiesel and the recovery of the catalyst after the transesterification process are the major challenges to be addressed in biodiesel production. In the present work, a cheap and promising solid base oxide catalyst was synthesized from chicken eggshell by calcination at 900 ℃ forming catalyst eggshells(CES) and was impregnated with the nanomagnetic material(Fe3O4) to obtain Fe3O4 loaded catalytic eggshell(CES–Fe3O4). Fe3O4 nanomaterials were synthesized by co-precipitation method and were loaded in catalytic eggshell by sonication, for better recovery of the catalyst after transesterification process. CES–Fe3O4 material was characterized by Thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy, a vibrating-sample magnetometer, Brunauer-Emmett-Teller, Dynamic light scattering, and Scanning electron microscopy. Biodiesel was synthesized by transesterification of Pongamia pinnata raw oil with 1:12 oil to methanol molar ratio and 2 wt% catalyst loading for 2 h at a temperature of 65 ℃ and yields were compared. The reusability of the catalyst was studied by the transesterification of the raw oil and its catalytic activity was found to be retained up to 7 cycles with a yield of 98%.

Intensification of levofloxacin sono-degradation in a US/H_2O_2 system with Fe_3O_4 magnetic nanoparticles

Fe3O4 magnetic nanoparticles(MNPs) were synthesised, characterised, and used as a peroxidase mimetic to accelerate levofloxacin sono-degradation in an ultrasound(US)/H2O2 system. The Fe3O4 MNPs were in nanometre scale with an average diameter of approximately 12 to 18 nm. The introduction of Fe3O4 MNPs increased levofloxacin sono-degradation in the US/H2O2 system. Experimental parameters, such as Fe3O4 MNP dose, initial solution p H, and H2O2 concentration, were investigated by a one-factor-at-a-time approach. The results showed that Fe3O4 MNPs enhanced levofloxacin removal in the p H range from 4.0 to 9.0. Levofloxacin removal ratio increased with Fe3O4 MNP dose up to 1.0 g·L-1and with H2O2 concentration until reaching the maximum. Moreover, three main intermediate compounds were identified by HPLC with electrospray ionisation tandem mass spectrometry, and a possible degradation pathway was proposed. This study suggests that combination of H2O2, Fe3O4 MNPs and US is a good way to improve the degradation efficiency of antibiotics.

Characteristics of magnetic Fe_3O_4 nanoparticles encapsulated with human serum albumin

Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin（HSA） for magnetic resonance imaging as contrast agent. Characteristics of magnetic particles coated or uncoated were carried out using scanning electron microscopy and X-ray diffraction. Zeta potentials, package effects and distributions of colloid particles were measured to confirm the attachment of HSA on magnetic particles. Effects of Fe3O4 nanoparticles coated with HSA on magnetic resonance imaging were investigated with rats. The experimental results show that the adsorption of HSA on magnetic particles is very favorable to dispersing of magnetic Fe3O4 particles, while the sizes of Fe3O4 particles coated are related to the molar ratio of Fe3O4 to HSA. The diameters of the majority of particles coated are less than 100 nm. Fe3O4 nanoparticle coated with HSA has a good biocompatibility and low toxicity. This new contrast agent has some effects on the nuclear magnetic resonance imaging of liver and the lowest dosage is 20μmol/kg for the demands of diagnosis.

Modification of Fe_3O_4 Magnetic Nanoparticles by L-dopa or Dopamine as an Enzyme Support

Fe3O4 magnetic nanoparticles were prepared by co-precipitation of Fe^2＋ and Fe^3＋ in an ammonia solution, and its size was about 36 nm measured by an atomic force microscope. Fe3O4 magnetic nanoparticles were modified by L-dopa or dopamine using sonication method. The analysis of FTIR clearly indicated the formation of Fe-O-C bond. Direct immobilization of trypsin （EC： 3.4.21.4） on Fe3O4 magnetic nanoparticles with L-dopa and dopamine spacer was investigated using glutaraldehyde as a coupling agent. No significant changes in the size and magnetic property of the three kinds of magnetic nanoparticles linked with or without trypsin were observed. The existence of the spacer molecule on magnetic nanoparticles could greatly improve the activity and the storage stability of bound trypsin through increasing the flexibility of enzyme and changing the microenvironment on nanoparticles surface compared to the naked magnetic nanoparticles.

Fe_3O_4 Magnetic Nanoparticles Modified Electrode as a Sensor for Determination of Nimesulide

A novel type of Fe3O4 nanoparticles modified glass carbon electrode（Fe3O4/GCE） was constructed and the electrochemical properties of N-（4-nitro-2-phenoxyphenyl）methanesulfonamide（nimesulide） were studied on the Fe3O4/GCE.In 0.4mol/L HAc-NaAc buffer solution（pH=5.0）,the electrode process of nimesulide was irreversible at bare GCE and Fe3O4/GCE.The Fe3O4/GCE exhibited a remarkable catalytic and enhancement effect on the reduction of nimesulide.The reduction peak potential of nimesulide shifted positively from-0.683 V at bare GCE to-0.625 V at Fe3O4/GCE,and the sensitivity was increased by ca.3 times.Some experimental conditions were optimized.The linear range between the peak current and the concentration of nimesulide was 2.6×10-6 ＂1.0×10-4mol/L（R=0.993） with a detection limit of 1.3×10-7mol/L.This method has been used to determine the content of nimesulide in medical tablets.The recovery was determined to be 96.9% ＂101.9% by means of standard addition method.The method is comparable to UV-Vis spectrometry.

Surface Enhanced Raman Spectroscopy of 4-Mercaptopyridine Molecules on Pb_3O_4 Nanoparticles

The surface enhanced Raman scattering （SERS） technique has been developed greatly since its first discovery nearly twenty-nine years ago. It is a very attractive technique for the detection of various organic and inorganic molecules due to its sensitivity and selectivity. However, the most critical aspect for performing a SERS experiment is the choice and fabrication of the substrates. For many yeas, SERS has been still restricted primarily to the usage of detecting analytes adsorbed onto coinage（Au, Ag or Cu） or alkali（ Li, Na or K） rough metallic surfaces. Recently, Quagliano reported SERS from molecules adsorbed on InAs/GaAs semiconductor quantum dots for the first time. Until now, few reports on semiconductor materials as the SERS substrates have been noted. Herein, we report our successful attempt to gain high signal-to-noise ratio （S/N） SERS spectra of 4-mercaptopyridine （ 4-Mpy ） adsorbed on Pb3O4 nanopaticles.

基于Fe@Fe3O4诊断和治疗平台的研究进展

Fe@Fe3O4纳米粒子(NPs)由于Fe核的存在具有很大的饱和磁化率和横向弛豫率,能够表现出比Fe3O4NPs更好的磁共振成像(MRI)和光/磁热治疗效果,并且由于其具备光声和磁共振(MR)造影功能,可引导Fe@Fe3O4NPs对肿瘤进行治疗.该材料因生物相容性好、成像和治疗方式多元化等优点而受到越来越多的关注.通过介绍和总结Fe@Fe3O4NPs的几种成像模式和治疗方式,描述了目前该材料的最新研究进展,以深入了解Fe@Fe3O4NPs在癌症治疗中的潜在应用.

Synthesis and Characterization of Superparamagnetic Fe₃O₄@SiO₂Core-Shell Composite Nanoparticles

The Fe3O4@SiO2 composite nanoparticles were obtained from as-synthesized magnetite (Fe3O4) nanoparticles through the modified St?ber method. Then, the Fe3O4 nanoparticles and Fe3O4@SiO2 composite nanoparticles were characterized by means of X-ray diffraction (XRD), Raman spectra, scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). Recently, the studies focus on how to improve the dispersion of composite particle and achieve good magnetic performance. Hence effects of the volume ratio of tetraethyl orthosilicate (TEOS) and magnetite colloid on the structural, morphological and magnetic properties of the composite nanoparticles were systematically investi-gated. The results revealed that the Fe3O4@SiO2 had better thermal stability and dispersion than the magnetite nanoparticles. Furthermore, the particle size and magnetic property of the Fe3O4@SiO2 composite nanoparticles can be adjusted by changing the volume ratio of TEOS and magnetite colloid.

Static magnetic field-assisted synthesis of Fe3O4 nanoparticles and their adsorption of Mn(Ⅱ) in aqueous solution

A facile method for synthesis of the magnetic Fe_3O_4 nanoparticles was introduced.Magnetic nanoparticles were prepared via co-precipitation method with(PMF) and without(AMF) 0.15 T static magnetic field.The effects of magnetic field on the properties of magnetic nanoparticles were studied by XRD,TEM,SEM,VSM and BET.The results showed that the magnetic field in the co-precipitation reaction process did not result in the phase change of the Fe_3O_4 nanoparticles but improved the crystallinity.The morphology of Fe_3O_4 nanoparticles was varied from random spherical particles to rod-like cluster structure.The VSM results indicated that the saturation magnetization value of the Fe_3O_4 nanoparticles was significantly improved by the magnetic field.The BET of Fe_3O_4nanoparticles prepared with the magnetic field was larger than the control by 23.5%.The batch adsorption experiments of Mn(Ⅱ) on the PMF and AMF Fe_3O_4 nanoparticles showed that the Mn(II) equilibrium capacity was increased with the pH value increased.At pH 8,the Mn(Ⅱ) adsorption capacity for the PMF and AMF Fe_3O_4 was reached at 36.81 and 28.36 mg·g^(-1),respectively.The pseudo-second-order model fitted better the kinetic models and the Freundlich model fitted isotherm model well for both PMF and AMF Fe_3O_4.The results suggested that magnetic nanoparticles prepared by the magnetic field presented a fairly good potential as an adsorbent for an efficient removal of Mn(Ⅱ) from aqueous solution.

Field-variable magnetic domain characterization of individual 10 nm Fe3O4 nanoparticles

The local detection of magnetic domains of isolated 10 nm Fe3O4 magnetic nanoparticles(MNPs) has been achieved by field-variable magnetic force microscopy(MFM) with high spatial resolution.The domain configuration of an individual MNP shows a typical dipolar response.The magnetization reversal of MNP domains is governed by a coherent rotation mechanism, which is consistent with the theoretical results given by micromagnetic calculations.Present results suggest that the field-variable MFM has great potential in providing nanoscale magnetic information on magnetic nanostructures,such as nanoparticles, nanodots, skyrmions, and vortices, with high spatial resolution.This is crucial for the development and application of magnetic nanostructures and devices.

Controllable Synthesis and Magnetic Properties of Monodisperse Fe_3O_4 Nanoparticles

Magnetite （Fe3O4） nanoparticles with different sizes and shapes are synthesized by the thermal decomposition method. Two approaches, non-injection one-pot and hot-injection methods, are designed to investigate the growth mechanism in detail. It is found that the size and shape of nanoparticles are determined by adjusting the precursor concentration and duration time, which can be well explained by the mechanism based on the LaMer model in our synthetic system. The monodisperse Fe3O4 nanoparticles have a mean diameter from 5nm to 16nm, and shape evolution from spherical to triangular and cubic. The magnetic properties are size-dependent, and Fe3O4 nanoparticles in small size about 5 nm exhibit superparamagnetie properties at room temperature and maximum saturation magnetization approaches to 78 emu/g, whereas Fe3O4 nanoparticles develop ferromagnetic properties when the diameter increases to about 16nm.