Modification of Nano-α-Al2O3 and Its Influence on the Surface Properties of Waterborne Polyurethane Resin Composite Passivation Films

Silane coupling agent KH560 was used to modify the surface of nano-α-Al2O3 in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al2O3 was determined by nano-particle size analyzer, and the effects of nano-α-Al2O3 content, ethanol-aqueous solution ratio and KH560 dosage on the dispersion and particle size of nano-α-Al2O3 were investigated. The material structure before and after modification was determined by Fourier transform infrared spectroscopy (FTIR). Aqueous polyurethane resin and inorganic components are combined with modified nano-α-Al2O3 dispersion to form chromium-free passivation solution. The solution is coated on the galvanized sheet, the adhesion and surface hardness are tested, the bonding strength of the coating and the surface hardness of the substrate are discussed. The corrosion resistance and surface morphology of the matrix were investigated by electrochemical test, neutral salt spray test and scanning electron microscope test. The chromium-free passivation film formed after the modification of nano-α-Al2O3 increases the surface hardness of galvanized sheet by about 85%. The corrosion resistance of the film is better than that of a single polyurethane film. The results show that the surface hardness and corrosion resistance of polyurethane resin composite passivation film are significantly improved by the introduction of nano-α-Al2O3.

One-pot hydrothermal fabrication of α-Fe_2O_3@C nanocomposites for electrochemical energy storage

A facile hydrothermal method was developed for the preparation of Fe_2O_3@C nanocomposites using FeCl_3·6H_2O as iron source and glucose as carbon source under alkaline condition. The morphology and structure of the as-prepared product were identified by transmission electron microscopy(TEM), high resolution transmission electron microscopy(HRTEM), field-emission scanning electron microscopy(FESEM),X-ray diffraction(XRD), Raman spectroscopy, Fourier Transform infrared spectroscopy(FTIR), and thermogravimetric analysis(TGA). The as-prepare α-Fe_2O_3@C nanocomposites were employed for supercapacitor electrode material. The synergistic combination of carbon electrical double-layer capacitance and α-Fe_2O_3 pseudo-capacitance established such nanocomposites as versatile platform for high performance supercapacitors. The synthesis method developed here is expected to obtain other metal oxide/carbon composite.

Enhancement of catalytic activity by homo-dispersing S_2O_8^(2–)-Fe_2O_3 nanoparticles on SBA-15 through ultrasonic adsorption

Mesoporous superacids S2O82–-Fe2O3/SBA-15(SFS)with active nanoparticles are prepared by ultrasonic adsorption method.This method is adopted to ensure a homo-dispersed nanoparticle active phase,large specific surface area and many acidic sites.Compared with bulk S2O82–-Fe2O3,Br?nsted acid catalysts and other reported catalysts,SFS with an Fe2O3 loading of 30%(SFS-30)exhibits an outstanding activity in the probe reaction of alcoholysis of styrene oxide by methanol with 100%yield.Moreover,SFS-30 also shows a more excellent catalytic performance than bulk S2O82–-Fe2O3 towards the alcoholysis of other ROHs(R=C2H5-C4H9).Lewis and Bronsted acid sites on the SFS-30 surfaces are confirmed by pyridine adsorbed infrared spectra.The highly efficient catalytic activity of SFS-30 may be attributed to the synergistic effect from the nano-effect of S2O82–-Fe2O3 nanoparticles and the mesostructure of SBA-15.Finally,SFS-30 shows a good catalytic reusability,providing an 84.1%yield after seven catalytic cycles.

Photoluminescence behavior and visible light photocatalytic activity of ZnO,ZnO/ZnS and ZnO/ZnS/α-Fe_2O_3 nanocomposites

In order to achieve effective, economic, and easily achievable photocatalyst for the degradation of dye methyl orange（MeO）, ZnO, ZnO/ZnS and ZnO/ZnS/α-Fe2O3 nanocomposites were prepared by simple chemical synthetic route in the aqueous medium. Phase, crystallinity, surface structure and surface behavior of the synthesized materials were determined by X-ray diffraction（XRD） and Brunauer-Emmett-Teller analysis（BET） techniques. XRD study established formation of good crystalline ZnO, ZnO/ZnS and ZnO/ZnS/α-Fe2O3 nanomaterials. By using intensity of constituent peaks in the XRD pattern, the compositions of nanocomposites were determined. From the BET analysis, the prepared materials show mesoporous behavior, type Ⅳ curves along with H4 hysteresis. The ZnO/ZnS/α-Fe2O3 composite shows the largest surface area among three materials. From the UV-visible spectra, the band gap energy of the materials was determined. Photoluminescence spectra（PL） were used to determine the emission behavior and surface defects in the materials. In PL spectra, the intensity of UV peak of ZnO/ZnS is lowered than that of ZnO while in case of ZnO/ZnS/α-Fe2O3, the intensity further decreased. The visible emission spectra of ZnO/ZnS increased compared with ZnO while in ZnO/ZnS/α-Fe2O3 it is further increased compared with ZnO/ZnS. The as-synthesized materials were used as photocatalysts for the degradation of dye MeO. The photo-degradation data revealed that the ZnO/ZnS/α-Fe2O3 is the best photocatalyst among three specimens for the degradation of dye MeO. The decrease of intensity of UV emission peak and the increase of intensity of visible emission cause the decrease of recombination of electrons and holes which are ultimately responsible for the highest photocatalytic activity of ZnO/ZnS/α-Fe2O3.

Catalysis of Nanometer α-Fe_2O_3 on the Thermal Decomposition of AP

Nanometer α-Fe2O3 catalysts were prepared by hydrolyzation in high temperature. Three kinds of precipitators, NaOH, （NH4）2CO3 and urea were used to compare the effect in the process of hydrolyzation. Nanometer sizer, transmission electron microscopy （TEM） and X-ray diffraction （XRD） were employed to test the profiles and diameters of the product particles. The test results indicate that the production is nanometer α-Fe2O3 with narrow particle size distribution （PSD） and good dispersibility. The catalysts are mixed with ammonia perchlorate （AP） in 1.0 wt.%. And the composite particles of catalysts with AP are prepared using a new solvent-nonsolvent method. Differential thermal analyzer （DTA） is employed to analysis the thermal decomposition of the composite particles and pure AP sample. The results imply that the thermal decomposition curve peaks of the samples in which nanometer α-Fe2O3 catalysts are added appear comparatively more ahead than that of pure AP sample. Among these mixtures added nanometer material, the smaller the particle diameter of catalyst is, the more ahead the thermal decomposition curve peaks of AP appear. The high and low temperature thermal decomposition curve peaks of AP mixed with the catalyst deposed by urea are more ahead of 77.8?℃ and 9.7?℃ than that of pure AP, respectively. The mechanism of the catalyst deposed by urea with smaller diameter and the distinct catalysis of the particles on the thermal decomposition of AP are discussed.

Growth of Carbon Nanocoils by Porous α-Fe2O3/SnO2 Catalyst and Its Buckypaper for High Efficient Adsorption

High-purity(99%)carbon nanocoils(CNCs)have been synthesized by using porousα-Fe2O3/SnO2 catalyst.The yield of CNCs reaches 9,098%after a 6 h growth.This value is much higher than the previously reported data,indicating that this method is promising to synthesize high-purity CNCs on a large scale.It is considered that an appropriate proportion of Fe and Sn,proper particle size distribution,and a loose-porous aggregate structure of the catalyst are the key points to the high-purity growth of CNCs.Benefiting from the high-purity preparation,a CNC Buckypaper was successfully prepared and the electrical,mechanical,and electrochemical properties were investigated comprehensively.Furthermore,as one of the practical applications,the CNC Buckypaper was successfully utilized as an efficient adsorbent for the removal of methylene blue dye from wastewater with an adsorption efficiency of 90.9%.This study provides a facile and economical route for preparing high-purity CNCs,which is suitable for large-quantity production.Furthermore,the fabrication of macroscopic CNC Buckypaper provides promising alternative of adsorbent or other practical applications.

Preparation of α-Fe_2O_3 Nanodisks by Blocking the Growth of (001) Plane

Based on the difference of hydroxy group configuration on the special adsorption and coordination of phosphate on the dispersed α-Fe2O3 nanodisks with diameter of 150-200 nm different planes of α-Fe2O3 nanoparticles, using （001） plane of α-Fe2O3, well-crystallized and well and thickness of 40-80 nm were synthesized via a hydrotherrnal method. The magnetic properties of synthesized nanodisks were investigated. It was found that the nanodisks possessed a saturation magnetization （Ms） of 0.38 emu/g, a rernanent magnetization （Mr） of 0.031 ernu/g and a coercivity of 452.91 Oe at room temperature. The Mr and coercivity of synthesized α-Fe2O3 nanodisks are higher and the Ms is lower than those of other previously reported α-Fe2O3 nanostructures.

Highly reliable and selective ethanol sensor based on α-Fe2O3 nanorhombs working in realistic environments

A highly reliable and selective ethanol gas sensor working in realistic environments based on alpha-Fe2O3(α-Fe2O3)nanorhombs is developed. The sensor is fabricated by integrating α-Fe2O3 nanorhombs onto a low power microheater based on micro-electro-mechanical systems(MEMS) technology. The α-Fe2O3 nanorhombs, prepared via a solvothermal method, is characterized by transmission electron microscopy(TEM), Raman spectroscopy, x-ray diffraction(XRD), and x-ray photoelectron spectroscopy(XPS). The sensing performances of the α-Fe2O3 sensor to various toxic gases are investigated. The optimum sensing temperature is found to be about 280℃. The sensor shows excellent selectivity to ethanol.For various ethanol concentrations(1 ppm-20 ppm), the response and recovery times are around 3 s and 15 s at the working temperature of 280℃, respectively. Specifically, the α-Fe2O3 sensor exhibits a response shift less than 6% to ethanol at280℃ when the relative humidity(RH) increases from 30% to 70%. The good tolerance to humidity variation makes the sensor suitable for reliable applications in Internet of Things(IoT) in realistic environments. In addition, the sensor shows great long-term repeatability and stability towards ethanol. A possible gas sensing mechanism is proposed.

α-Fe_2O_3 nanoplates with superior electrochemical performance for lithium-ion batteries

On account of the high theoretical capacity, high corrosion resistance, environmental benignity, abundant availability and low cost, the research on a-Fe_2O_3 has been gradually fastened on as promising anodes materials toward lithium-ion batteries(LIBs). A high-performance anode for LIBs based on α-Fe_2O_3 nanoplates have been selectively prepared. The α-Fe_2O_3 nanoplates can be synthesized with iron ionbased ionic liquid as iron source and template. The α-Fe_2O_3 nanoplates as the anode of LIBs can display high capacity of around1950 mAh g^(-1) at 0.5 A g^(-1) which have exceeded the theoretical capacity of α-Fe_2O_3. On account of unique nanoplate structures and gum arabic as binder, the α-Fe_2O_3 nanoplates also exhibit high rate capability and excellent cycling performance.

Structural and Mechanistic Studies of γ-Fe2O3 Nanoparticle as Capecitabine Drug Nanocarrier

Using density functional theory,noncovalent interactions and four mechanisms of covalent functionalization of capecitabine anticancer drug onto γ-Fe2O3 nanoparticles have been investigated.Quantum molecular descriptors of noncovalent configurations were studied.It was specified that binding of capecitabine onto γ-Fe2O3 nanoparticles is thermodynamically suitable.Hardness and the gap of energy between LUMO and HOMO of capecitabine are higher than the noncovalent configurations,showing the reactivity of capecitabine increases in the presence of γ-Fe2O3 nanoparticles.Capecitabine can bond to γ-Fe2O3 nanoparticles through OH（k1 mechanism）,NH（k2 mechanism）,CO（k3 mechanism） and F（k4 mechanism） groups.The activation energies,activation enthalpies and activation Gibbs free energies of these reactions were calculated.It was specified that the k1 and k2 mechanisms are under thermodynamic control and k3 and k4 under kinetic control.These results could be generalized to other similar drugs.

磁性壳聚糖/γ-Fe_2O_3复合膜吸附甲基橙性能研究

以壳聚糖、γ-Fe2O3为原料,采用流延法制备磁性壳聚糖/纳米γ-Fe2O3复合膜,以甲基橙溶液作为目标污染物,考察了吸附剂用量、溶液初始质量浓度、pH、共存阴离子等对吸附效果的影响,并对吸附动力学、热力学进行了初步探讨.结果表明:在pH=2.91、无共存阴离子的条件下,吸附效果最佳,去除率随着吸附剂用量的增加而提高.无机阴离子的存在对吸附容量有显著影响.壳聚糖/纳米γ-Fe2O3复合膜对甲基橙偶氮染料的吸附等温线符合Langmuir模型,吸附过程符合拟二级动力学方程,内扩散为主要控速步骤.吸附是熵推动的自发放热过程,低温有利于反应的进行.

固相法制备α-Fe_2O_3纳米粒子

用固相反应法合成了纳米α－Ｆｅ２Ｏ３粒子。采用ＸＲＤ、ＴＥＭ、Ｍｏｓｓｂａｕｅｒ对合成样品进行表征，结果表明此方法合成的粒子为α－Ｆｅ２Ｏ３．其粒子呈花生型，粒子直径为２０～４０ｎｍ左右．

纳米γ-Fe_2O_3粒子的制备及其性能研究

以乙二醇作为前驱体,采用溶胶——凝胶法制备出了纳米γ-Fe2O3粒子,讨论了灼烧温度等对粒子大小、形貌、磁性等的影响,并采用红外光谱、X射线衍射光谱、透射电子显微镜、比表面分析仪及振动样品磁强计等对粒子的性能进行表征.结果表明:当烧结温度为450℃时,实验所得到的粒子的粒径最小,为5nm左右,磁性最强,比饱和磁化强度为65 emu.g-1,且分散较均匀.

纳米ɑ-Fe_2O_3改性聚乙烯醇基蜂蜡复合涂膜材料工艺优化

为有效的提高聚乙烯醇(polyvinyl alcohol,PVA)的成膜后阻湿性能,该研究采用乳化剂聚甘油酯和单甘酯复配乳化蜂蜡使其与PVA形成稳定的乳液。在PVA基膜材料中添加了蜂蜡及纳米α-Fe2O3,利用单因素试验确定了响应曲面试验的因素水平,从而使用响应面试验研究了两者之间对成膜透湿率的影响和交互作用。结果表明:随着蜂蜡添加量增加纳米α-Fe2O3添加量临界值降低且有效降低成膜透湿率,所以这2种材料之间存在明显的交互作用(P<0.05)。回归优化的最优组蜂蜡添加量为0.739 g/100mL,纳米α-Fe2O3添加量为0.04 g/100mL时透湿率达到最低点,比对照组膜降低了73.76%(P<0.05)。优化的膜材料具有明显的抑菌效果,在光催化条件下,能使大肠杆菌菌落总数下降1个数量级。

纳米α-Fe_2O_3-TiO_2改性海藻酸钠/壳聚糖双极膜制备与表征

在壳聚糖(CS)阴离子交换膜中添加纳米复合半导体材料α-Fe2O3-TiO2,制备了PVA-SA/α-Fe2O3-TiO2-CS双极膜(PVA:聚乙烯醇;SA:海藻酸钠),并用扫描电镜、热重分析、电子万能试验机和接触角测定仪等对其进行了表征。研究结果表明,添加纳米α-Fe2O3-TiO2可提高双极膜的亲水性、热稳定性和机械性能。纳米α-Fe2O3-TiO2复合半导体材料较纳米α-Fe2O3或纳米TiO2单一半导体材料具有更强的光催化双极膜中间界面层水解离能力,在高压汞灯照射下能大大降低双极膜的膜阻抗和膜电阻压降(IR降)。

导电聚苯胺与磁性γ-Fe_2O_3纳米复合物的电磁性能

Nanocomposites of PAn-DBSA/γ-Fe 2O 3 with electrical and ferromagnetic behavior(σ= 2.18×10 -3-5.00×10 -5 S/cm, M s=3.7-16.6 m 2·A/kg, H c=8 805.2-9 133.1 A/m) were prepared by a chemical modification-redoping method in a neutral medium. The products were characterized by TEM, XRD, UV-Vis, four-probe method, and magnetometer. The results indicate that the electrical and magnetic properties of the nanocomposites strongly depend on γ-Fe 2O 3 content. With the increase of γ-Fe 2O 3 content, the electrical conductivity is decreased and saturation magnetization is increased.

新型燃烧合成方法制备α-Fe_2O_3纳米晶

将聚乙烯醇 (PVA)作为络合剂与硝酸铁反应 ,不调节反应体系的 p H值成功地制备出α- Fe2 O3纳米晶。络合物在 15 0℃反应后的产物灰烬经 X射线分析 ,含有部分α- Fe2 O3和γ- Fe2 O3,产物灰烬经 40 0℃煅烧 1.5 h后得到的是α- Fe2 O3和γ- Fe2 O3的混合物 ,X射线衍射和红外光谱分析的结果显示 ,此时有机组分已分解完全。在 45 0℃煅烧1.5 h,γ- Fe2 O3全部转变为α- Fe2 O3,经透射电镜观察晶粒尺寸在 2 5～ 35 nm之间 ,且为球形 ,在 5 0 0℃的温度下煅烧得到的产物晶粒比 45 0℃煅烧产物晶粒稍有长大 ,在 2 5～ 40

煅烧温度对Mn改性γ-Fe_2O_3催化剂结构及低温SCR脱硝活性的影响

采用共沉淀法,在不同煅烧温度下制备一系列Mn改性γ-Fe2O3催化剂（Fe0.7M n0.3Oz）,研究了煅烧温度对Fe0.7M n0.3Oz催化剂低温SCR脱硝活性的影响,并借助XRD、N2吸附-脱附、EDS及SEM等手段对催化剂进行表征。结果表明,350℃煅烧所得Fe0.7M n0.3Oz催化剂的低温SCR活性最佳,在70℃时取得92%的NOx转化率,100~200℃可维持100%的NOx转化率,而450℃煅烧所得催化剂的低温SCR活性最低;煅烧温度为350℃时,催化剂具有最大的比表面积和比孔容、发达的孔隙结构及适当结晶度的γ-Fe2O3,而煅烧温度为400或450℃时,催化剂发生烧结且有α-Fe2O3生成,不利于低温SCR反应的进行,因此,Fe0.7M n0.3Oz催化剂的最佳煅烧温度为350℃。

均分散超微细α-Fe_2O_3水溶胶的制备

Cubic and ellipsoide ultrafine monodispersed hematite colloidal particles wereprepared by hydrothermal reaction from Fe（OH）3 get in the presence of Sn4+ ions. Thenumbers of nuclei increase with the concentration of Sn4+ ions. The initial concentrationof Fe（OH）3 gel might approach to 0.5 mol.L- 1. The products were characterized by TEMand XRD.

络合物型溶胶 - 凝胶过程研制纳米晶γ-Fe_2O_3磁粉

本文与传统的柠檬酸盐方法不同，首次直接以柠檬酸铁为起始物质，经由络合物型溶胶凝胶过程非醇盐法制得超细的铁棕磁粉。使用ＤＴＡ、ＸＲＤ、ＦＴＩＲ、ＳＥＭ、ＢＥＴ以及磁天平等测试手段，表征了试样的特性，证明产物为纳米晶γＦｅ２Ｏ３，具有良好的磁性，ＸＲＤ给出了原始晶粒的精确尺寸３０．４ｎｍ，并与ＢＥＴ所测平均团粒尺寸１４７ｎｍ加以比较。讨论了络合物型溶胶凝胶过程的最适宜工艺条件和某些反应机理。