核-壳结构磁性金属有机骨架材料Fe3O4@UiO-66-NH2的合成、表征及催化性能

UiO-66-NH_2是以Zr4+为金属,以2-氨基对苯二甲酸为配体制备得到的金属有机骨架材料,它是目前报道中具有较高热稳定性和化学稳定性的材料之一。本文以Fe_3O_4为核,以UiO-66-NH_2为壳,采用层层自组装方法制备了核-壳结构的磁性金属有机骨架材料Fe_3O_4@UiO-66-NH_2。利用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)和氮气吸附等对其进行了表征,并考察了该磁性材料在克脑文盖尔(Knoevenagel)缩合反应中的催化性能。结果表明,该磁性材料Fe_3O_4@UiO-66-NH_2为核-壳结构,壳层厚度约为100 nm,氨基含量为1.70 mmol·g-1。该磁性复合材料具有Fe_3O_4和UiO-66-NH_2的双重功能,既可以磁性分离,又具有UiO-66-NH_2的孔结构和催化性能。由于壳层材料中Lewis酸性位(Zr4+)和碱性基团(-NH_2)的协同催化能力及其壳层的纳米尺寸效应,该磁性材料在Knoevenagel缩合反应中表现出和UiO-66-NH_2纳米粒子相当的催化活性。而且,通过磁性分离实现催化剂的多次循环使用后,其结构没有明显变化。     

氨基化修饰介孔Fe3O4@SiO2@mSiO2磁性核壳复合微球的可控制备及吸附性能

以水热法制备的高磁饱和强度Fe₃O₄纳米颗粒为核,正硅酸乙酯（TEOS）为前驱体,采用改进的Stöber法,制备介孔SiO₂包覆Fe₃O₄磁性核壳复合微球。利用XRD、SEM、TEM、N₂吸-脱附、FTIR和VSM对制备样品的物相结构、形貌和磁性能进行了测试表征。研究结果表明,制备的复合材料呈球形,粒径分布均一,材料的比表面积和磁饱和强度分别为413 m²·g^-1和68.93 emu·g^-1。研究了TEOS的添加量对复合微球形貌的影响,随着TEOS添加量的增加,SiO₂壳层增厚,复合粒子形貌均匀,饱和磁化强度有所下降,仍具有良好的超顺磁性。在此基础上,通过接枝法在复合微球的表面接枝-NH₂,制备了一种新型磁性纳米吸附剂（Fe₃O₄@SiO₂@mSiO₂-NH₂）,进而研究了其对水中重金属离子Cr（Ⅳ）的吸附性能。通过动力学拟合,Fe₃O₄@SiO₂@mSiO₂-NH₂对Cr（Ⅳ）的吸附过程是准二级动力学模型占主导地位。探究了该材料对Cr（Ⅳ）的吸附过程和吸附机理。结果表明,其吸附机理及吸附容量与Cr（Ⅳ）的离子形态及-NH₂有关,并通过吸附剂与吸附质之间的电子共用或静电吸附实现。     

磁性UiO-66复合材料的合成及其对水体中硝基酚有机分子的吸附性能

以溶剂热法制备了Fe₃O₄@SiO₂-PSS@UiO-66结构的磁性多孔复合材料,并利用XRD,TEM,SEM,IR,TG,VSM 和N₂吸附-脱附对样品的结构和形貌进行测试表征。研究结果表明：磁性UiO-66复合材料是以球型Fe₃O₄为核,MOF为壳的核-壳结构,其表面的MOF层由多个立方多晶堆积组装而成,且具有良好的超顺磁性。进一步研究了Fe₃O₄@SiO₂-PSS@UiO-66对2-硝基-1,3-苯二酚的吸附性能。探讨了吸附时间,吸附量和2-硝基-1,3-苯二酚初始浓度在吸附过程中的影响,结果表明：当吸附时间为12 h,吸附剂的用量为5 mg,2-硝基-1,3-苯二酚浓度为400 mg·L^-1时,最大吸附量为161.36 mg·g^-1。另外,磁性UiO-66复合材料对2-硝基-1,3-苯二酚高的吸附性能可能是由于UiO-66与2-硝基-1,3-苯二酚之间的静电作用以及二者之间苯环的π-π作用。     

Fe3O4@SiO2@mTiO2介孔多功能纳米复合颗粒的制备及载药能力

以溶剂热法制备氨基功能化的Fe₃O₄纳米颗粒为磁核,结合溶胶-凝胶法和模板法在其表面先后包覆上致密的SiO₂层和介孔TiO₂层,制备了磁性-发光-微波热转换性-介孔结构为一体的多功能核-壳结构纳米复合颗粒,并对其结构、性能及载药能力进行了研究。XRD分析表明:Fe₃O₄表面包覆上了无定形结构的SiO₂和TiO₂。TEM照片表明:所得的纳米复合颗粒具有明显的核壳结构和完美的球形,构成核的Fe₃O₄颗粒的尺寸在40~50 nm之间,Fe₃O₄@SiO₂@mTiO₂核壳结构纳米复合颗粒的尺寸为60~70 nm,壳层厚度约10 nm,并可观察到壳层中清晰的孔状结构。磁性、荧光光谱和微波热转换特性分析表明:该复合颗粒同时具有良好的发光性、磁性和微波热转换特性。N₂气吸附及药物负载率分析表明,该复合颗粒具有较高的比表面积(640 m²·g^-1)和介孔结构(孔径约2.8 nm)并且具有较高的药物负载率。     

用于高效去除水中孔雀石绿的三层结构磁性复合材料Fe3O4@聚丙烯酸@ZiF-8的制备

设计并合成了一种以磁性纳米粒子为核，聚合物为中间层，金属有机骨架材料为外层的三层结构磁性复合材料(Fe₃O₄@PAA@ZIF 8)。首先利用溶剂热法制备Fe₃O₄纳米粒子，然后通过蒸馏沉淀聚合法在Fe₃O₄纳米粒子表面包覆聚丙烯酸(PAA)层，最后通过原位沉积法在PAA外部包覆ZIF 8。在对Fe₃O₄@PAA@ZIF 8的组成和结构进行表征的基础上，深入研究其对孔雀石绿(MG)的吸附性能。透射电子显微镜(TEM)显示 Fe₃O₄@PAA@ZIF 8 具有明显的三层结构，Fe₃O₄的平均粒径为 117nm，PAA 层厚度约为 17 nm，ZIF 8层的厚度约为 14 nm。Fe₃O₄@PAA@ZIF 8对 MG 的吸附量随着 pH 的升高而增大，吸附过程符合准二阶动力学模型和 Langmuir等温吸附模型。此外，Fe₃O₄@PAA@ZIF 8还表现出良好的重复利用性能，8次循环利用后对MG(500 mg·L^-1)的最大吸附量仍可达982 mg·g^-1。     

纳米Fe3O4及Ni2 掺杂Fe3O4的制备、表征及吸附Pb(Ⅱ)的特性

采用一种改进的共沉淀法制备了纳米磁铁矿(Fe₃O₄)及Ni²⁺掺杂磁铁矿(Ni_xFe_3-xO₄,x=0.1,0.3,0.6),用X-射线衍射(XRD)、扫描电镜(SEM)、氮气物理性吸附、酸碱滴定等手段对产物进行了表征,用平衡吸附法研究了4种样品对Pb(Ⅱ)离子的吸附容量及吸附模型。结果表明,Fe₃O₄和3种Ni_xFe_3-xO₄均为近似球形的单相晶质纳米颗粒;与Fe₃O₄比较,Ni_xFe_3-xO₄的颗粒尺寸变小、表面电荷零点和pH＝5.0时的表面正电荷量降低;样品的孔体积、比表面积和表面分形度以及表面羟基含量都随产物中Ni²⁺掺杂量的增加而升高。4种样品对Pb(Ⅱ)的等温吸附数据均适合用Langmuir模型拟合(R²=0.9942~0.9858),其相关系数的大小表现为：Fe₃O₄>Ni_0.1Fe_2.9O₄>Ni_0.3Fe_2.7O₄=Ni_0.6Fe_2.4O₄;Freundlich模型对样品等温吸附Pb(Ⅱ)的实验数据拟合度较低(R²=0.981 3~0.947 7),4种样品的Freundlich相关系数的大小关系与Langmuir相关系数相反。初始pH=5.0时,Fe₃O₄,Ni_0.1Fe_2.9O₄,Ni_0.3Fe_2.7O₄和Ni_0.6Fe_2.4O₄对Pb(Ⅱ)的最大吸附容量分别为6.02,6.68,7.29和8.34 mg·g^-1。可见,Ni_xFe_3-xO₄(尤其是Ni²⁺掺杂量较高的产物)对水环境中重金属Pb(Ⅱ)的去除能力明显高于Fe₃O₄。     

双功能化磁性纳米修复剂对多重金属的快速、高效钝化行为

采用“一锅法”制备了四氧化三铁/半胱氨酸（Fe₃O₄/Cys）磁性纳米微球,随后对Fe₃O₄/Cys进行亚氨基二乙酸（IDA）修饰得到Fe₃O₄/Cys/IDA磁性双功能化纳米微球。研究发现Fe₃O₄/Cys中的L-Cys是通过—SH基团接枝到Fe₃O₄表面的,随后IDA分子中的羧基与Fe₃O₄/Cys中的—NH₂形成酰胺键,最终形成多支链多羧基的Fe₃O₄/Cys/IDA磁性纳米修复剂。基于修复剂表面短支链-长支链交替的多羧基结构,实现了羧基基团的高密度接枝。同时,Fe₃O₄/Cys/IDA磁性纳米微球对Pb²⁺、Cd²⁺、Cu²⁺、Co²⁺、Ni²⁺、Zn²⁺为专性吸附,而对Hg²⁺属于非专性吸附,且吸附重金属后得到的钝化产物均表现了良好的稳定性。另外,Fe₃O₄/Cys/IDA对重金属离子的吸附符合Langmuir模型,属于单层均相吸附,其吸附过程符合准二级动力学模型,最大吸附量为49.05 mg·g^-1。     

可回收Fe3O4@SiO2-Ag磁性纳米微球对染料污染物的快速脱色处理

介绍了一种采用无毒廉价的前驱物制备Fe₃O₄@SiO₂-Ag磁性纳米微球的快捷方法,制备的Fe₃O₄@SiO₂-Ag纳米微球在NaBH₄存在下可以催化还原染料污染物.实验结果表明,Fe₃O₄@SiO₂-Ag磁性纳米粒子保持了Ag纳米粒子和Fe₃O₄纳米粒子的双重优点,不仅对染料罗丹明B和曙红Y具有良好的催化还原效率,而且可以在外加磁场作用下从溶液中快速有效的分离.催化还原反应速率与反应温度及Fe₃O₄@SiO₂-Ag催化剂用量有关,反应体系中表面活性剂和无机盐(Na₂SO₄)的存在也会影响催化剂的催化活性.该Fe₃O₄@SiO₂-Ag磁性纳米粒子在工业染料污染物处理方面具有应用前景.     

Bi2Fe4O9/g-C3N4/UiO-66三元复合材料的协同光催化作用

通过水热法合成具有协同机制的三元复合材料Bi₂Fe₄O₉/g-C₃N₄/UiO-66,研究表明三元复合光催化剂的催化活性要高于二元材料和纯材料。这主要是由于Bi₂Fe₄O₉更易于和g-C₃N₄结合形成稳定的Z-scheme异质结结构,使三元复合材料增强了可见光响应能力,提高了电子-空穴分离能力,增强了空穴和电子的氧化还原能力。     

Bi2Fe4O9/g-C3N4/UiO-66三元复合材料的协同光催化作用

通过水热法合成具有协同机制的三元复合材料Bi₂Fe₄O₉/g-C₃N₄/UiO-66,研究表明三元复合光催化剂的催化活性要高于二元材料和纯材料。这主要是由于Bi₂Fe₄O₉更易于和g-C₃N₄结合形成稳定的Z-scheme异质结结构,使三元复合材料增强了可见光响应能力,提高了电子-空穴分离能力,增强了空穴和电子的氧化还原能力。     

Sol-gel synthesis of K3InF6 and structural characterization of K2InC10O10H6F9, K3InC12O14H4F18 and K3InC12O12F18

K₃InF₆ is synthesized by a sol-gel route starting from indium and potassium acetates dissolved in isopropanol in the stoichiometry 1:3, with trifluoroacetic acid as fluorinating agent. The crystal structures of the organic precursors were solved by X-ray diffraction methods on single crystals. Three organic compounds were isolated and identified: K₂InC₁₀O₁₀H₆F₉, K₃InC₁₂O₁₄H₄F₁₈ and K₃InC₁₂O₁₂F₁₈. The first one, deficient in potassium in comparison with the initial stoichiometry, is unstable. In its crystal structure, acetate as well as trifluoroacetate anions are coordinated to the indium atom. The two other precursors are obtained, respectively, by quick and slow evaporation of the solution. They correspond to the final organic compounds, which give K₃InF₆ by decomposition at high temperature. The crystal structure of K₃InC₁₂O₁₄H₄F₁₈ is characterized by complex anions [In(CF₃COO)₄(OH_x)₂]^(5−2x)− and isolated [CF₃COOH_2−x]^(x−1)− molecules with x=2 or 1, surrounded by K⁺ cations. The crystal structure of K₃InC₁₂O₁₂F₁₈ is only constituted by complex anions [In(CF₃COO)₆]³⁻ and K⁺ cations. For all these compounds, potassium cations ensure only the electroneutrality of the structure. IR spectra of K₂InC₁₀O₁₀H₆F₉ and K₃InC₁₂O₁₂F₁₈ were also performed at room temperature on pulverized crystals.     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

Non-centrosymmetric Ba3Ti3O6(BO3)2

The compound previously reported as Ba₂Ti₂B₂O₉ has been reformulated as Ba₃Ti₃B₂O₁₂, or Ba₃Ti₃O₆(BO₃)₂, a new barium titanium oxoborate. Small single crystals have been recovered from a melt with a composition of BaTiO₃:BaTiB₂O₆ (molar ratio) cooled between 1100°C and 850°C. The crystal structure has been determined by X-ray diffraction: hexagonal system, non-centrosymmetric space group, a=8.7377(11) Å, c=3.9147(8) Å, Z=1, wR(F²)=0.039 for 504 unique reflections. Ba₃Ti₃O₆(BO₃)₂ is isostructural with K₃Ta₃O₆(BO₃)₂. Preliminary measurements of nonlinear optical properties on microcrystalline samples show that the second harmonic generation efficiency of Ba₃Ti₃O₆(BO₃)₂ is equal to 95% of that of LiNbO₃.     

A new 2212-type stair like structure: Bi14Sr21Fe12O61, m=5 member of the generic [Bi2Sr3Fe2O9]m[Bi4Sr6Fe2O16] family

A new oxide, Bi₁₄Sr₂₁Fe₁₂O_61, with a layered structure derived from the 2212 modulated type structure Bi₂Sr₃Fe₂O₉, was isolated. It crystallizes in the I2 space group, with the following parameters: a=16.58(3) Å, b=5.496(1) Å, c=35.27(2) Å and β=90.62°. The single crystal X-ray structure determination, coupled with electron microscopy, shows that this ferrite is the m=5 member of the [Bi₂Sr₃Fe₂O₉]_m[Bi₄Sr₆Fe₂O₁₆] collapsed family. This new collapsed structure can be described as slices of 2212 structure of five bismuth polyhedra thick along , shifted with respect to each other and interconnected by means of [Bi₄Sr₆Fe₂O₁₆] slices. The latter are the place of numerous defects like iron or strontium for bismuth substitution; they can be correlated to intergrowth defects with other members of the family.     

Ion-beam irradiation of lanthanum compounds in the systems La2O3-Al2O3 and La2O3-TiO2

Thin crystals of La₂O₃, LaAlO₃, La_2/3TiO₃, La₂TiO₅, and La₂Ti₂O₇ have been irradiated in situ using 1 MeV Kr²⁺ ions at the Intermediate Voltage Electron Microscope-Tandem User Facility (IVEM-Tandem), Argonne National Laboratory (ANL). We observed that La₂O₃ remained crystalline to a fluence greater than 3.1×10¹⁶ ions cm⁻² at a temperature of 50 K. The four binary oxide compounds in the two systems were observed through the crystalline-amorphous transition as a function of ion fluence and temperature. Results from the ion irradiations give critical temperatures for amorphisation (T_c) of 647 K for LaAlO₃, 840 K for La₂Ti₂O₇, 865 K for La_2/3TiO₃, and 1027 K for La₂TiO₅. The T_c values observed in this study, together with previous data for Al₂O₃ and TiO₂, are discussed with reference to the melting points for the La₂O₃-Al₂O₃ and La₂O₃-TiO₂ systems and the different local environments within the four crystal structures. Results suggest that there is an observable inverse correlation between T_c and melting temperature (T_m) in the two systems. More complex relationships exist between T_c and crystal structure, with the stoichiometric perovskite LaAlO₃ being the most resistant to amorphisation.     

Synthesis, crystal structure, infrared and Raman spectra of Sr4Cu3(AsO4)2(AsO3OH)4·3H2O and Ba2Cu4(AsO4)2(AsO3OH)3

The two new compounds, Sr₄Cu₃(AsO₄)₂(AsO₃OH)₄·3H₂O (1) and Ba₂Cu₄(AsO₄)₂(AsO₃OH)₃(2), were synthesized under hydrothermal conditions. They represent previously unknown structure types and are the first compounds synthesized in the systems SrO/BaO-CuO-As₂O₅-H₂O. Their crystal structures were determined by single-crystal X-ray diffraction [space group C2/c, a=18.536(4) Å, b=5.179(1) Å, c=24.898(5) Å, β=93.67(3)°, V=2344.0(8) Å³, Z=4 for 1; space group P4₂/n, a=7.775(1) Å, c=13.698(3) Å, V=828.1(2) Å³, Z=2 for 2]. The crystal structure of 1 is related to a group of compounds formed by Cu²⁺-(XO₄)³⁻ layers (X=P⁵⁺, As⁵⁺) linked by M cations (M=alkali, alkaline earth, Pb²⁺, or Ag⁺) and partly by hydrogen bonds. In 1, worth mentioning is the very short hydrogen bond length, D···A=2.477(3) Å. It is one of the examples of extremely short hydrogen bonds, where the donor and acceptor are crystallographically different. Compound 2 represents a layered structure consisting of Cu₂O₈ centrosymmetric dimers crosslinked by As1φ₄ tetrahedra, where φ is O or OH, which are interconnected by Ba, As2 and hydrogen bonds to form a three-dimensional network. The layers are formed by Cu₂O₈ centrosymmetric dimers of CuO₅ edge-sharing polyhedra, crosslinked by As1O₄ tetrahedra. Vibrational spectra (FTIR and Raman) of both compounds are described. The spectroscopic manifestation of the very short hydrogen bond in 1, and ABC-like spectra in 2 were discussed.     

Raman scattering investigations on lanthanum-doped Bi4Ti3O12-SrBi4Ti4O15 intergrowth ferroelectrics

The ferroelectric ceramics of Bi₄Ti₃O₁₂, SrBi₄Ti₄O₁₅, and lanthanum-doped Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅ were synthesized, and their Raman spectra were investigated. La-doping resulted in the enlargement of remnant polarization of Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅. The structure of the Bi₂O₂ layers and TiO₆ octahedra of the intergrowth was found to be different from those of Bi₄Ti₃O₁₂ and SrBi₄Ti₄O₁₅. La³⁺ ions exhibit pronounced selectivity for the occupation of A site as La content is lower than 0.50, and tend to be incorporated into Bi₂O₂ layers when the La content is higher than 0.50. Lanthanum substitution brings about the structural phase transition in Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅. The variation of ferroelectric property may be attributed to combined contribution from the decreasing of the oxygen vacancies, the relaxation of the lattice distortion, the destroying of the insulation and the space charge compensation effects of the Bi₂O₂ slabs.     

g-C_3N_4/CaTi_2O_5复合材料制备及其光催化性能

利用类石墨氮化碳(g-C_3N_4)和亚稳相钙钛氧化物(CaTi_2O_5)固相法制备C_3N_4/CaTi_2O_5复合材料。利用X射线衍射(XRD)、金相显微镜、扫描电子显微镜(SEM)及附带能谱分析仪(EDS)和N2吸附-脱附对样品的显微结构和比表面积进行检测分析,并用紫外-可见吸收光度计(UV-Vis)测试了样品的光吸收性能,研究C_3N_4与CaTi_2O_5物质的量之比(nC_3N_4/nCaTi_2O_5)对C_3N_4/CaTi_2O_5复合样品的物相结构和微观形貌的影响,同时考察C_3N_4/CaTi_2O_5复合样品在可见光照射下光催化降解罗丹明染料效果。实验结果表明:相比纯C_3N_4和CaTi_2O_5样品,C_3N_4/CaTi_2O_5复合样品在可见光下具有较高的光催化性能,随着nC_3N_4/nCaTi_2O_5增加,样品的光催化降解率随之增加而后降低,当nC_3N_4/nCaTi_2O_5=1∶1时,样品的光催化降解率达到最大值99.5%,并且循环重复利用5次后,样品的光催化剂降解率仍几乎保持不变。复合样品光催化性能提高主要归因于复合能级结构有效地抑制了电子和空穴复合所致。     

Magnetic diphase nanostructure of ZnFe2O4/γ-Fe2O3

Magnetic diphase nanostructures of ZnFe₂O₄/γ-Fe₂O₃ were synthesized by a solvothermal method. The formation reactions were optimized by tuning the initial molar ratios of Fe/Zn. All samples were characterized by X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, and Raman spectra. It is found that when the initial molar ratio of Fe/Zn is larger than 2, a diphase magnetic nanostructure of ZnFe₂O₄/γ-Fe₂O₃ was formed, in which the presence of ZnFe₂O₄ enhanced the thermal stability of γ-Fe₂O₃. Further increasing the initial molar ratio of Fe/Zn larger than 6 destabilized the diphase nanostructure and yielded traces of secondary phase α-Fe₂O₃. The grain surfaces of diphase nanostructure exhibited a spin-glass-like structure. At room temperature, all diphase nanostructures are superparamagnetic with saturation magnetization being increased with γ-Fe₂O₃ content.     

g-C3N4/CaTi2O5复合材料制备及其光催化性能

利用类石墨氮化碳（g-C₃N₄）和亚稳相钙钛氧化物（CaTi₂O₅）固相法制备C₃N₄/CaTi₂O₅复合材料。利用X射线衍射（XRD）、金相显微镜、扫描电子显微镜（SEM）及附带能谱分析仪（EDS）和N₂吸附-脱附对样品的显微结构和比表面积进行检测分析,并用紫外-可见吸收光度计（UV-Vis）测试了样品的光吸收性能,研究C₃N₄与CaTi₂O₅物质的量之比（n_C3N4/nCaTi₂O₅）对C₃N₄/CaTi₂O₅复合样品的物相结构和微观形貌的影响,同时考察C₃N₄/CaTi₂O₅复合样品在可见光照射下光催化降解罗丹明染料效果。实验结果表明：相比纯C₃N₄和CaTi₂O₅样品,C₃N₄/CaTi₂O₅复合样品在可见光下具有较高的光催化性能,随着n_C3N4/nCaTi₂O₅增加,样品的光催化降解率随之增加而后降低,当n_C3N4/nCaTi₂O₅=1：1时,样品的光催化降解率达到最大值99.5%,并且循环重复利用5次后,样品的光催化剂降解率仍几乎保持不变。复合样品光催化性能提高主要归因于复合能级结构有效地抑制了电子和空穴复合所致。