g-C3 N4/Fe3 O4磁性纳米复合材料 去除水中对硝基酚的研究

采用溶剂热法,以g-C_3N_4为基体制备g-C_3N_4/Fe_3O_4磁性纳米复合材料,并将其作为吸附剂,研究了不同的吸附条件对g-C_3N_4/Fe_3O_4去除水中对硝基酚性能的影响,并利用Langmuir和Freundlich等温线模型分析了该吸附行为。结果表明,在投料量为10 mg,吸附时间为5 min时,对硝基酚的去除率达到85.7%;吸附等温线拟合结果表明g-C_3N_4/Fe_3O_4对对硝基酚的吸附行为更符合Langmuir等温模型,相关系数为0.9943。     

TiO_2/g-C_3N_4复合物的制备及其光催化性能

通过简单的水热法在石墨相氮化碳(g-C3N4)纳米片层上原位生成TiO_2纳米颗粒。制备出的TiO_2/g-C3N4纳米复合材料在可见光照射下光催化活性显著高于纯g-C3N4。当TiO_2负载量为30%(质量分数)时,反应40min即可降解97%的罗丹明B(RhB)。光生电子在TiO_2和g-C3N4界面间的传输使得光生载流子分离,光催化性能提高。提出TiO_2/g-C3N4复合材料在可见光照射条件下的光催化机理并通过实验进行了验证。结果表明,TiO_2/gC3N4反应体系中起氧化作用的是空穴(h+)和超氧自由基(·O-2)。     

无压烧结Si_3N_4－MgAl_2O_4－Al_2O_3系复合材料

本文对ｓｉ＿３Ｎ＿４－ＭｇＡｌ＿２Ｏ＿４－Ａｌ＿２Ｏ＿３系复合材料的无压烧结进行了研究。讨论了Ａ１＿２Ｏ＿３含量对材料性能的影响及烧结工艺对材料性能和显微结构的相互关系。实验表明：两段法烧结可以得到性能良好的Ｓｉ＿３Ｎ＿４－ＭｇＡｌ＿２Ｏ＿４－Ａｌ＿２Ｏ＿３复合材料     

Dielectric and Magnetic Properties of (1-x)CaTiO_3-xNi_(0.5)Zn_(0.5)Fe_2O_4 Composite Ceramics

(1-x)CaTiO_3-xNi_(0.5)Zn_(0.5)Fe_2O_4(0 x 1.0) composite ceramics were synthesized by a conventional solid state reaction method.The phase formation,microstructure,and dielectric and magnetic properties were investigated by X-ray diffraction,scanning electron microscopy,precision impedance analysis,and vibrating sample magnetometry,respectively.The results indicate that the composite ceramics are composed of both perovskite phase Ca TiO_3 and spinel phase Ni_(0.5)Zn_(0.5)Fe_2O_4.The maximal relative density for 0.5CaTiO_3-xNi_(0.5)Zn_(0.5)Fe_2O_4 composite ceramics reaches 97.8%,as it has been sintered at the temperature of 1260 ℃ for 3 h.Dielectric constant and loss tangent of(1-x)CaTiO_3-xNi_(0.5)Zn_(0.5)Fe_2O_4 composite ceramics show dispersion in the low frequency range.Their phase transition temperature of the dielectric constant shifts to lower temperatures with the increase of Ni_(0.5)Zn_(0.5)Fe_2O_4 content.This phenomenon is attributed to that the phase transition temperature of CaTiO_3 is higher than that of Ni_(0.5)Zn_(0.5)Fe_2O_4.The saturation magnetization of (1-x)CaTiO_3-xNi_(0.5)Zn_(0.5)Fe_2O_4 composite ceramics increases with the Ni_(0.5)Zn_(0.5)Fe_2O_4 ferrite content.     

Bi_2O_3/TiO_2复合光催化剂对甲基橙的光催化作用

以溶胶-凝胶法制备了Bi2O3/TiO2复合光催化剂,用TEM、HRTEM、XRD、Raman、FTIR、PL、UV-Vis DRS等对其结构、性质进行表征,并以甲基橙为有机污染物对Bi2O3/TiO2复合光催化剂活性进行研究。结果表明:复合少量Bi2O3可抑制TiO2由锐钛矿相到金红石相相变及其颗粒的生长。n(Bi)∶n(Ti)=0.017 5配比的Bi2O3/TiO2复合光催化剂活性最好,当用量为2.5g/L时,25mg/L的甲基橙溶液在500 W氙灯下照射5h后,脱色率达到99.4%,2.1倍于Degussa P25TiO2。     

g-C_3N_4/LSACF复合材料制备及其可见光催化性能研究

在将生物质海绵-丝瓜络纤维通过高温碳化烧制成丝瓜络基活性炭纤维(LSACF)的基础上,以尿素包裹并煅烧制得g-C_3N_4/LSACF复合材料。通过SEM、XRD、EDS、BET等手段对样品微观结构和组成进行表征,通过UV-Vis分析其可见光响应性。结果表明:复合材料对罗丹明B(RhB)有着良好的吸附和可见光催化降解性能,优良的吸附性能源于LSACF的网状多孔结构及负载后复合材料比表面积的有效提高;g-C_3N_4/LSACF在5次循环降解测试中仍维持较好的催化性能,显示了其良好的循环利用价值。该研究为g-C_3N_4负载材料的选择及高效循环利用提供了思路。     

Fabrication and Magnetic Properties of Composite Ni_(0.5)Zn_(0.5)Fe_2O_4/Pb(Zr_(0.52)Ti_(0.48))O_3 Nanofibers by Electrospinning

One-dimensional and quasi-one-dimensional nanostructure materials are promising building blocks for electromagnetic devices and nanosystems.In this work,the composite Ni0.5Zn0.5Fe2O4(NZFO)/ Pb(Zr0.52Ti0.48)O3(PZT) nanofibers with average diameters about 65 nm are prepared by electrospinning from poly(vinyl pyrrolidone) (PVP) and metal salts.The precursor composite NZFO/PZT/PVP nanofibers and the subsequent calcined NZFO/PZT nanofibers are investigated by Fourier transform infrared spectroscopy (FT- IR) ,X-ray diffraction (XRD),scanning electron microscopy (SEM).The magnetic properties for nanofibers are measured by vibrating sample magnetometer(VSM).The NZFO/PZT nanofibers obtained at calcination temperature of 900 °C for 2 h consist of the ferromagnetic spinel NZFO and ferroelectric perovskite PZT phases,which are constructed from about 37 nm NZFO and 17 nm PZT grains.The saturation magnetization of these NZFO/PZT nanofibers increases with increasing calcination temperature and contents of NZFO in the composite.     

介晶结构四氧化三铁纳米粒子的一种简易合成方法

采用氯化铁、氢氧化钠和少量水在乙二醇中进行常压加热反应得到了尺寸可控、形貌均匀的介晶结构四氧化三铁纳米粒子。所得纳米粒子饱和磁化强度为72.6 emu·g~(-1),既具有超顺磁性,又表现快速的磁响应特性。体系中少量水分的存在十分重要,没有水的参与反应不能进行。随着水加入量的增加,所得纳米粒子的尺寸逐渐变小。     

TiO_2/ZnO/Ni_(0.5)Zn_(0.5)Fe_2O_4磁载光催化剂的制备及其光催化性能

采用均匀沉淀法制备了镍锌铁氧体、纳米TiO2-ZnO复合粉体和镍锌铁氧体负载纳米TiO2-ZnO复合粉体,并用XRD对所制粉体进行了表征。发现所制得的纳米TiO2为锐钛矿型、镍锌铁氧体为尖晶石型。以甲基橙溶液为模拟废水,考察了纳米TiO2-ZnO复合粉体和镍锌铁氧体负载纳米TiO2-ZnO复合粉体的光催化活性。研究还发现镍锌铁氧体负载纳米TiO2-ZnO粉体后仍具有良好的磁性能,可通过增加外磁场进行分离。     

Preparation and Photocatalytic Performance of Double-Shelled Hollow W_(18)O_(49)@C_3N_4@Ti_3C_2 Microspheres

C₃N₄,C₃N₄@Ti₃C₂ and W₁₈O₄₉@C₃N₄@Ti₃C₂ hollow spheres were successfully prepared by using SiO₂ template followed by gradual deposition method.The degradation of phenol solution and photolysis ability were tested to characterize its photocatalytic activity.Compared with the single-shelled C₃N₄ and C₃N₄@Ti₃     

Influence of Mechanical Milling on Photocatalytic Activity of g-C_3N_4 Prepared by Heating Melamine

Using X-ray diffraction,transmission electron microscopy,Brunauer-Emmett-Teller surface area measurement,ultraviolet-visible diffuse reflection spectra,and photoluminescence spectroscopy,the effect of mechanical milling on the photocatalytic activity of g-C3N4 photocatalyst was investigated.The rhodamine B,as a photodegrading goal,was used to evaluate the photocatalytic activity of g-C3N4.The experimental results indicate that the milling treatment is an effective method to improve the photocatalytic activity of g-C3N4.The enhanced photocatalytic activity was attributed to the improvement in catalyst's surface area and dye adsorption on catalyst surface.Moreover,checking the luminescence properties of g-C3N4,it is found that the photocatalytic active sites on g-C3N4 are likely the same as luminescence sites.     

NiO-ZrxCel-xO2催化剂的制备及其性能

用尿素均匀沉淀法制备了NiO-ZrxCe-xO2复合氧化物,并用XRD、TPR、TPD和原位红外对其晶相结构、NiO与载体的相互作用、催化剂的表面酸碱性能和NiO-ZrxCe1-xO2对CO2和CH3OH吸附性等进行了表征。结果表明,Zr0.7Ce0.3O3形成固溶体,且表面具有酸性中心和碱性中心,除NiO-Zr0.1Ce0.9O2样品外,各催化剂均能使CH3OH发生解离吸附,而CO2在各催化剂表面发生了单齿吸附,在金属位上发生了线式吸附和剪式吸附,在金属位和酸性位的协同作用下发生了卧式吸附。NiO-Zr0.7Ce0.3O2催化剂在CO2和CH3OH常压合成碳酸二甲酯（DMC）反应中表现出较好的催化活性和选择性。     

铌铁酸锶-钛酸铅铁电固溶体的合成与性能研究

通过铌铁矿预合成法制备了(1-x)Sr(Fe1/2Nb1/2)O3-xPbTiO3(SFN-PT)铁电陶瓷。XRD测量表明,合成的SFN-PT陶瓷为纯钙钛矿结构。随着PbTiO3(PT)摩尔分数的增加,SFN-PT陶瓷的晶体结构从三方相向四方相转变,其介电响应也从弥散的宽峰变得比较尖锐,并伴随着介电常数峰值温度(Tm)的升高。少量的MnO2或Li2CO3掺杂能有效地降低SFN-PT陶瓷的介电损耗。SFN-PT陶瓷呈现典型的P-E电滞回线,但是剩余极化强度较小,少量的MnO2或Li2CO3掺杂能明显地降低矫顽场、增大剩余极化强度。SFN-PT陶瓷的压电应变常量d33较小,随着组分的不同,d值在10～22pC/N之间变化。     

在V_2O_5、Sb_2O_3、Bi_2O_3、Fe_2O_3、K_2O/Al_2O_3催化剂上邻二甲苯的氨氧化

本文论述了邻二甲苯氨氧化合成邻苯二甲腈的最佳工艺条件,载在高温热处理的三氧化二铝上的 V_2O_s、Sb_2O_3、Bi_2O_3、Fe_2O_3、K_2O 催化剂,对生成邻苯二甲腈表现出良好的活性及选择性,其选择率>95%。催化剂的酸度是一个关键因素.     

Two Dimension C_3N_4/MoS_2 Nanocomposites with Enhanced Photocatalytic Hydrogen Evolution under Visible Light Irradiation

MoS_2-decorated C_3N_4(C_3N_4/MoS_2) nanosheets hybrid photocatalysts were prepared by a simple sonication-impregnation method. Face-to-face lamellar heterojunctions were well established between two dimension(2D) C_3N_4 and MoS_2 nanosheets. The effects of MoS_2 content on the light absorption, charge transfer and photocatalytic activity of the hybrid samples were investigated. Characterization results show that MoS_2 nanosheets are well anchored on the face of C_3N_4 nanosheets and the composites have well dispersed layered morphology. After loading with MoS_2, the light absorption of composites was much improved, especially in visible-light region. The photocatalytic activities of C_3N_4/MoS_2 samples were evaluated based on the H_2 evolution under visible light irradiation(λ 400 nm). When the loading amount of MoS_2 was increased to 5 wt%, the highest H_2 evolution rate(274 μmol·g~(-1)·h~(-1)) was obtained. Compared with samples obtained from direct impregnation method, sonication pretreatment is favorable for the formation of 2D layered heterojuctions and thus improve the photocatalytic activity. Slightly deactivation of C_3N_4/MoS_2 composites could be observed when recycled due to the mild photocorrosion of MoS_2. Based on the band alignments of C_3N_4 and MoS_2, a possible photocatalytic mechanism was discussed, where MoS_2 could efficiently promote the separation of the photogenerated carriers of C_3N_4.     

Synthesis and Characterization of Biomimetic Fe_3O_4/Coke Magnetic Nanoparticles Composite Material

A composite material(Fe_3O_4/Coke)using coke supported Fe_3O_4 magnetic nanoparticles was successfully prepared via an in-situ chemicaloxidation precipitation method and characterized by SEM,XRD,Raman,and FTIR.The results showed that the Fe_3O_4 nanoparticles existed steadily on the surface of coke,with better dispersing and smaller particle size.The catalytic ability of Fe_3O_4/Coke were investigatied by degrading p-nitrophenol(P-NP).The results showed that the apparent rate constant for the P-NP at 1.0 g·L~(-1) catalyst,30 mmol·L~(-1) H_2O_2,pH=3.0,30 ℃ and the best ratio of Coke/Fe_3O_4 0.6,was evaluated to be 0.027 min~(-1),the removalrate of CODCr was 75.47%,and the dissolubility of Fe was 2.42 mg·L~(-1).Compared with pure Fe_3O_4,the catalytic ability of Fe_3O_4/Coke in the presence of H_2O_2 was greatly enhanced.And Fe_3O_4/Coke was a green and environmentalcatalyst with high catalytic activity,showing a good chemicalstability and reusability.     

Magnetically Recoverable PEI/Titanate@Fe_3O_4 Photocatalysts: Fabrication and Photocatalytic Properties

The magnetically separable ternary polyetherimide/titanate@Fe_3 O_4(PTF) photocatalysts of special heterostructure between magnetite(Fe_3 O_4) microspheres and titanates nanosheets modified by polyetherimide(PEI) were successfully fabricated via a simple facile hydrothermal deposition method. The as-prepared photocatalysts were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Transmission electron microscopy and UV-vis diffuse reflectance spectroscopy etc. The results showed that the as-fabricated material had a structure of Fe_3 O_4 microspheres coated with titanates nanosheets modified by PEI. The special interfacial contact between 3 D microsphere and 2 D nanosheets in the nanoarchitectures was formed via electrostatic attraction. Furthermore, the resulted photocatalysts were tested by degradation reaction of methylene blue under visible light irradiation and demonstrated an enhanced performance than the pure Fe_3 O_4 microspheres, and the photocatalytic activity enhanced with the molar ratio of Fe_3 O_4 microspheres and modified titanate gradually, which was attributed to the expansion of the surface area and the different electrostatic contact between the Fe_3 O_4 microspheres and titanate nanosheets. Moreover, the obtained results revealed the high yield magnetic separation and efficient reusability of PTF-5(96.7%) over 3 times reuse.     

Fe_3O_4@PAM@NTA-Ni~(2+) Magnetic Composite Nanoparticles for Highly Specific Separation of His-tagged Proteins

A facile approach has been developed to synthesize Fe_3O_4@PAM(polyacrylamide) nanoparticles(NPs) with carboxyl groups on the surfaces by copolymerization with acrylamide and acrylic acid in Fe_3O_4 NPs aqueous suspension. Nitrilotriacetic acid(NTA) was conjugated to the magnetic NPs via well-known carboniimide chemistry using EDC and NHS. The Ni~(2+) ions loaded on the surface of NPs provide abundant docking sites for immobilization of His-tagged green fluorescent proteins(His-tagged GFP). The high magnetic property of Fe_3O_4@PAM@NTA-Ni~(2+) allows an easy separation of the NPs from solution under an external magnetic field, with high His-tagged protein binding capacity(42 μg protein/mg of NPs). The NPs can be recycled for at least four times without significant loss of binding capacity to proteins. These materials show great potential to separate His-tagged protein with low-cost purification at industrial scale.     

微波辐射法制备Fe_3O_4/P(MMA-AMPS)磁性微球

采用微波辐射法制备了油酸(OA)表面修饰的Fe_3O_4颗粒,透析后得到稳定的Fe_3O_4磁流体。在Fe_3O_4磁流体和十二烷基硫酸纳(SDS)的存在下,以甲基丙烯酸甲酯(MMA)和2-丙烯酰胺基-甲基丙磺酸(AMPS)为单体,采用微波辐射乳液聚合法制备了MMA-AMPS共聚物包覆Fe_3O_4磁性高分子微球,并对磁性高分子微球的形态与结构进行了表征,测定了磁性高分子微球的粒径、磁含量和饱和磁化强度。结果表明:在优化聚合反应条件下,通过微波辐射乳液聚合法可制备出粒径为0.25~0.50μm,饱和磁化强度为4.2emu·g-1的磁性高分子微球。     

CaxLa10-x(SiO4)6O3-x/2氧离子导体的制备及性能

由于在低温和低氧分压下具有比ZrO2固体电解质高的电导率,氧基磷灰石引起了研究者的关注.利用溶胶-凝胶法低温制备了硅酸盐磷灰石CaxLa10-x(SiO4)6O3-x/2 (x = 0, 0.5, 1.0 ,1.5和2),经TG-DTA、XRD、IR和SEM表征,所得产品为磷灰石相.以电化学阻抗谱研究了CaxLa10-x(SiO4)6O3-x/2的导电性能,发现随着间隙氧数量的增加,体系电导率逐渐增大,活化能却逐步减小.在700℃时La10(SiO4)6O3的电导率达到7.98×10-3Scm-1,比Ca2La8(SiO4)6O2提高21 000多倍.离子迁移数和氧分压对电导率的研究表明,主要的电荷载体是O2-,所制备的磷灰石为氧离子导体.