ZnFe2O4的制备及光催化性能研究

以乙二醇作为溶剂,采用溶剂热法制备ZnFe2O4,进一步通过控制煅烧温度获得具有不同晶粒尺寸的ZnFe2O4晶体.XRD和SEM分析表明,ZnFe2O4是由纳米尺寸的微晶构成的球状颗粒,粒径约200 nm,属于正尖晶石结构.UV-vis测定表明ZnFe2O4在紫外及可见光范围均有吸收,禁带宽度为1.60 ～2.18 eV,制备的温度条件对禁带能隙产生一定的影响.进一步以亚甲基蓝染料为研究对象考察了不同温度条件下制备的ZnFe2O4光催化活性,实验结果表明500℃煅烧的ZnFe2O4具有较高的染料降解率,当染料初始浓度10 mg/L,初始pH为11,催化剂用量为0.04 g/L,300 W汞灯照射2h,亚甲基蓝的降解率可达到96.8;,降解反应符合一级动力学.由于制备的ZnFe2O4具有磁性,重复使用三次亚甲基蓝的降解率仍可达到83.3;.     

NiFe2O4/g-C3N4的制备及可见光催化降解甲基橙

采用浸渍法制备不同负载量NiFe2 O4的负载型光催化剂NiFe2 O4/g-C3 N4,利用XRD、FT-IR、N2-adsorption、ICP-OES、TEM及XPS等手段表征NiFe2 O4/g-C3 N4样品,并考察其对甲基橙的可见光催化降解性能.结果表明,与NiFe2 O4和g-C3 N4样品相比,负载型NiFe2 O4/g-C3 N4样品对甲基橙具有更好的光催化降解活性,且催化活性随着NiFe2 O4负载量增大(0.5~5.0wt;)而呈现先增大再减小的趋势.NiFe2 O4负载量2.0wt;的样品2-NiFe/CN在可见光照射下对浓度5 mg·L-1的甲基橙表现出最好的降解活性和稳定性.这是因为能带宽度小(1.5 eV)的NiFe2 O4与能带宽度大(2.7 eV)的g-C3 N4形成的异质结催化剂NiFe2 O4/g-C3 N4,有效地促进光生载流子在二者界面快速传递和光生电子-空穴对的有效分离.     

棒状BiPO_4微晶的合成及其对模拟燃油催化氧化脱硫活性

以五水合硝酸铋和系列磷酸盐为起始原料,采用简单水热法制备棒状BiPO4粉体。采用XRD、SEM、EDS和UV-Vis吸收光谱等手段对其组成、纯度、形貌和光吸收特性进行表征;以金卤灯为实验光源,次甲基蓝为模型污染物,考察系列BiPO4光催化剂的的光催化活性;在此基础上,以二苯并噻吩为模拟含硫污染物探讨了所得BiPO4对模拟FCC汽油的光催化氧化脱硫(Photo-Cat-ODS)活性。SEM测试表明,所得BiPO4粉体均为棒状结构,且起始磷酸盐对产物的尺寸有一定的影响。光催化活性研究结果表明,在模拟太阳光照射下,所合成的系列BiPO4粉体对阳离子染料次甲基蓝有非常高的光催化降解活性,而且催化剂的形貌和尺寸对催化剂光催化活性的影响显著,当以磷酸二氢铵为原料时,所得样品NH2-BiPO4的活性最高。模拟FCC汽油光催化脱硫实验结果表明,空气为氧化剂条件下,NH2-BiPO4微晶对模拟FCC汽油具有较高的脱硫活性,模拟太阳光连续照射2 h,模拟汽油脱硫率高达90.5%。     

水热法制备Mn掺杂ZnO及其光催化性能研究

ZnO是一类具有广阔应用前景的光催化材料,但是光生载流子复合率高等问题限制了其进一步应用.本研究使用水热法制备了Mn掺杂ZnO粉体,测试了该粉体的物相组成、孔隙结构、发光性质和光催化性能.结果表明,当Mn替代0.5;Zn时,Mn占据了ZnO晶格中Zn的位置,粉体粒度小、比表面积大,抑制了光生载流子的复合,降低了禁带宽度,拓宽了光的响应范围.在8 W、365 nm紫外光条件下光照70 min后,制备的Mn0.05 Zn0.95 O粉体对刚果红降解率达到了97.4;,COD去除率达到了76.34;;Mn0.05 Zn0.95 O对罗丹明B吸附最好,对亚甲基蓝降解最好;对刚果红连续降解4个循环后,降解率降低了6.6;.该研究成果为光催化降解有机废水提供了技术支撑.     

铋基碘氧化物/煤矸石复合粉体的制备及光催化性能

以表面改性的煤矸石粉、硝酸铋和碘化钾为原料,采用超声法制备了BiOI/煤矸石复合粉体和Bi5 O7I/Bi4O5I2/煤矸石复合粉体,利用XRD、SEM、EDS对所制得的样品进行了表征,并以模拟太阳光为光源,罗丹明B为目标降解物,对其光催化活性进行了研究.结果表明:BiOI/煤矸石复合粉体和Bi5O7I/Bi4O5I2/煤矸石复合粉体均表现出较高的可见光光催化降解能力,并且Bi5O7I/Bi4O5I2/煤矸石复合粉体的光催化活性要大于BiOI/煤矸石复合粉体的光催化活性.Bi5O7I/Bi4O5I2/煤矸石复合粉体三次循环利用后光催化2h对罗丹明B的降解率仍可达到88.9;,可重复使用.     

BiFeO3-Bi24Fe2O39复合物的制备及可见光催化性能研究

以硝酸铁(Fe(NO3)3·9H2O)硝酸铋(Bi(NO3)3·5H2O)为原料,酒石酸作络合剂,聚乙二醇6000作分散剂,用溶胶-凝胶法制备了BiFeO3-Bi24Fe2 O39复合催化剂.用XRD、FT-IR、UV-vis、PL光谱、TG-DSC等对其结构进行了表征.以亚甲基蓝为目标化合物,评价了样品的可见光催化活性.结果表明,500℃煅烧2h的复合催化剂热稳定性好,荧光强度最强,禁带宽度最小,用500 W的长弧氙灯照射6h,亚甲基蓝降解率达到93.11;.     

三维花状复合材料Fe3O4-ZnO的制备与性能研究

以FeCl3、Zn(Ac)2、NH3· H2O等为原料,采用水热法制备了三维花状Fe3O4-ZnO磁性复合材料.通过SEM、XRD、XPS、ICP、UV-Vis DRS及VSM等对样品组成、结构等进行了表征,并以亚甲基蓝为目标降解物,考察了不同Fe/Zn摩尔比复合材料在紫外光照下的光催化活性.结果表明,n(Fe/Zn)为0.36时,Fe 3O4-ZnO复合材料表现出较优异的光催化活性,在180 min内对亚甲基蓝的降解率达到99.3;.SEM分析表明Fe3 O4-ZnO复合材料由六棱柱纳米棒自组装而成,与纯ZnO相比,该Fe3O4-ZnO复合材料紫外线吸收发生红移,拓展了ZnO的可见光响应.此外,该复合材料具有较强磁性(饱和磁化强度是24.91 emu/g),可通过外加磁场将其分离回收,重复使用四次后对亚甲基蓝的降解率仍达到95.5;.     

NiFe2O4磁性纳米颗粒的制备及其催化降解孔雀石绿的研究

以溶胶-凝胶法和固相研磨法制备NiFe2O4磁性纳米颗粒,采用X射线粉末衍射仪、扫描电子显微镜、透射电子显微镜、X射线光电子能谱仪、震动样品磁强计等探讨了不同合成方法对其结构、晶型、形貌的影响,结果表明凝胶-溶胶法制得的NiFe2O4具有颗粒小、尺寸均匀、磁学性能优、催化性能好等特点.推测了NiFe2O4/H2O2类芬顿体系催化降解孔雀石绿的反应机理.考察了pH值、催化剂用量、氧化剂用量、反应时间等因素的影响,结果表明:对浓度为25 mg/L的孔雀石绿溶液,当NiFe2O4用量为0.05 g,H2O2用量为0.30 mL,pH为5,温度为298 K,反应时间为45 min,孔雀石绿脱色率在93;以上.动力学研究表明降解过程近似为一级反应,速率常数达0.057 min-1.     

Zn3V2O8材料的水热法制备及其光学性质研究

采用水热法制备了纳米带状结构的Zn3 V2O8多晶粉体,并对Zn3 V2 O8漫反射光谱以及发射谱、激发谱进行了分析.结果表明,在230 ～450 nm波长范围为全吸收,激发谱上有一个宽带激发与窄带激发,峰值分别位于350 nm与272 nm.在发射谱上的宽带发射与窄带发射,峰值分别在528 nm与716 nm.降解率实验结果表明了当光照时间延长到3h后,水热合成Zn3 V2O8基本已完全降解亚甲基蓝溶液.     

V2O5/g-C3N4复合物的制备及可见光催化性能研究

以偏钒酸铵和尿素混合物为前驱体,混合煅烧制备了V2O5/g-C3N4复合物催化剂.用X射线衍射(XRD)、傅里叶红外光谱(FT-IR)、扫描电镜(SEM)、透射电镜(TEM)、紫外-可见光漫反射吸收光谱(UV-vis)、比表面积测试(BET)、光致发光谱(PL)等对其结构进行了表征.结果表明复合物中存在V2O5和g-C3N4形成异质结构,其禁带宽度减小、吸收带边红移,光催化效率有显著提高.以亚甲基蓝(MB)为目标化合物,评价了样品的光催化活性,当前躯体中尿素与NH4VO3质量比为10∶1,煅烧温度为500℃,煅烧时间为0.5h,催化剂活性最高.在60W日光灯照射40 min,对亚甲基蓝得降解率达到97.52;.     

CsI-LiCl共晶材料的坩埚下降法生长与闪烁性能研究

本文采用坩埚下降法,在真空密封的石英坩埚中成功生长出CsI-LiCl与CsI-LiCl:Na共晶闪烁体。通过扫描电子显微镜(SEM)观察晶体微结构表明该共晶中LiCl相与CsI相存在周期性的层状排列,CsI相的厚度在5 μm左右。共晶样品的X射线激发发射谱显示在CsI-LiCl和CsI-LiCl:Na共晶样品存在缺陷发光,在CsI-LiCl样品中还观察到了纯CsI的自陷激子(STE)发光。CsI-LiCl样品在α粒子激发下的多道能谱中观察到明显的全能峰,这一结果证明CsI-LiCl共晶可用于热中子探测的潜力。     

静电纺丝法制备CeO2微纳米纤维及其除氟性能

以聚丙烯腈(PAN)为载体,六水合硝酸铈[Ce(NO₃)₃·6H₂O]为原料,采用静电纺丝法制备了Ce(NO₃)₃/PAN纤维,在空气中热处理得到CeO₂微纳米纤维,通过XRD、BET和SEM对CeO₂微纳米纤维进行表征。采用静态吸附实验探讨了CeO₂微纳米纤维去除水溶液中氟离子的性能,考察了溶液pH值、初始氟离子浓度及共存阴离子等对吸附性能的影响。结果表明,pH=3时,CeO₂微纳米纤维对F^-的吸附性能最佳,CeO₂吸附量随着F^-浓度的增大呈上升趋势。CeO₂微纳米纤维对F^-的吸附等温线遵循Langmuir模型,二级动力学模型能很好地描述CeO₂微纳米纤维对F^-的吸附过程。CeO₂微纳米纤维的除氟性能优良,可为其实际应用提供理论参考。     

X-ray analysis of sideroxol from <Emphasis Type="Italic">Sideritis leptoclada</Emphasis>

Sideroxol (1), a kaurane diterpene which has the ent-7α,18-dihydroxy-15β,16β-epoxykaurane structure (MW = 320.47, C₂₀H₃₂O₃) was obtained from the acetone extract of Sideritis leptoclada plant as well as from some other Sideritis species. It crystallizes in the orthorhombic space group P2₁, 2₁, 2₁ with a = 10.967(3), b = 24.555(5), c = 6.372(4) Å, Dc = 1.240 g cm⁻³, Z = 4, and refines to R = 0.065 for 721 independent reflections. The skeleton consists of three fused six-membered rings and a five-membered ring with fused epoxide. The six membered rings exhibited slightly distorted chair conformation. In addition to sideroxol, two kaurane and five kaurene diterpenes were isolated from the hexane and acetone extracts of the studied plant.     

Photoluminescence characteristics of Mg- and Si-doped GaN thin films grown by MOCVD technique

We have studied the optical, structural and surface morphology of doped and undoped GaN thin films. The p- and n-type thin films have been successfully prepared by low-pressure MOCVD technique by doping with Mg and Si, respectively. The different carrier concentrations were obtained in the GaN thin films by varying dopant concentrations. Photoluminescence (PL) studies were carried to find the defect levels in the doped and undoped GaN thin films at low temperature. In the undoped GaN thin films, a low intensity and broad yellow band peak was observed. The donor–acceptor pair (DAP) emission and its phonon replicas were observed in both the Si or Mg lightly doped GaN thin films. The dominance of the blue and the yellow emissions increased in the PL spectra, as the carrier concentration was increased. The XRD and SEM analyses were employed to study the structural and surface morphology of the films, respectively. Both the doped and the undoped films exhibited hexagonal structure and polycrystalline nature. Mg-doped GaN thin films showed columnar structure whereas Si-doped films exhibited spherical shape grains.     

New zeotype borophosphates with chiral tetrahedral topology: (H)0.5M1.25(H2O)1.5[BP2O8]·H2O (M = Co(II) and Mn(II))

Two new isostructural open‐framework zeotype transition metal borophosphate compounds, (H)_0.5M_1.25(H₂O)_1.5[BP₂O₈]·H₂O (M = Co(II) and Mn(II)) were synthesized by mild hydrothermal method. The structure of compounds were characterized by single‐crystal X‐ray diffraction which have ordered, alternating, vertex‐sharing BO₄, PO₄, and (MO₄)OM(H₂O)₂ groups with hexagonal, P 6₁ 2 2 (No 178) space group and unit cell parameters for Co a = 9.4960(6) Å, c = 15.6230(13) Å, for Mn a = 9.6547(12) Å, c = 15.791(3) Å, Z = 1 for both of them. TGA/DTA analysis, IR spectroscopy were used for characterization. Magnetic susceptibility measurements for both of the compound indicate strong antiferromagnetic interaction between metal centers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Solubility of Ag2O into the Na2O–B2O3–Al2O3 system

The solubility of Ag₂O was measured for the Na₂O–B₂O₃ and Na₂O–B₂O₃–Al₂O₃ system with the rotating crucible method and static method, respectively, under air atmosphere at temperatures ranging from 1273 to 1423 K. The contamination of melts from crucibles could be avoided by the rotating crucible method, with which it became possible to measure the solubility of Ag₂O for the Na₂O–B₂O₃ system above the melting point of Ag for the first time. It was found that the addition of Na₂O decreases the solubility of Ag₂O while the addition of Al₂O₃ had little effect on the solubility. The effect of Na₂O and Al₂O₃ on the solubility of Ag₂O is expressed by interaction coefficients and is analyzed in terms of the basicity of melts. The solubility of Ag₂O in Na₂O–B₂O₃–Al₂O₃ melts increased with increased temperature. This phenomena was explained by a small enthalpy change in oxidation of silver.     

Considerations on the structure and physical properties of B2O3-SiO2 and GeO2-SiO2 glasses

Data of density, refractive index and thermal expansion coefficient for B₂O₃-SiO₂ and GeO_2-SiO₂ glasses have been analyzed. The volumes of the structural units are the same found for the vitreous B₂O₃, GeO₂ and SiO₂. The volume of any structural unit is constant over the entire composition region of the glass system. The same has been found for the differential refraction and unit refraction of the structural units in these glasses. Different features are observed for the differential expansion of the structural units. There is a considerable change with composition in the differential expansion of BO₃, GeO₄ and SiO₄ units. The effect is attributed to a change in the asymmetry of vibrations with the number of Si-O-B or Si-O-Ge linkages in the matrix. The thermal expansion coefficient is mainly determined by the contribution of B₂O₃ or GeO₂ in the concerned glasses.     

Molecular structure and crystal packing of uncomplexed 1,6-bis(N-cyano-p-methoxy-anilino)-2,4-hexadiyne, C22H18N4O2

The X-ray crystal structure of 1,6-bis(N-cyano-p-methoxy-anilino)-2,4-hexadiyne, C₂₂H₁₈N₄O₂, is determined. The crystal packing is dominated by phenyl stacking interactions. Weak C–H···N hydrogen bonds help align the molecules. C–H··· hydrogen bonding is not apparent.     

Structural and electrical properties of vapour phase grown Cd1 − xFexTe single crystals

Cd_1 − xFe_xTe single crystals were prepared by vapour phase growth method in the composition range of 0 ≤ x ≤ 0.03. Chemical analysis, surface morphology, structural investigations and electrical properties were carried out by EDAX, SEM, XRD, TEM and transport technique, respectively. Microscopic variations between the target and actual compositions were noticed. Morphology studies revealed that dislocation aided growth is active in the present crystals. TEM and XRD studies confirmed that the samples of all compositions crystallized in zinc blende structure, and the lattice parameters varied almost linearly decreases with Fe content. At room temperature, the resistivity of the Cd_1 − xFe_xTe crystals of all compositions (x = 0.01, 0.015, 0.02, 0.025 and 0.03) lies in the range of 3.5-6.5 M Ω, the activation energies lie in the range of 63-133 meV, and the samples were show the ‘p’ type conductivity.     

空位浓度对纤锌矿CdS电子结构和光学性质影响的第一性原理研究

本文基于密度泛函理论的平面波超软赝势方法,采用第一性原理研究了含Cd空位缺陷CdS和含S空位缺陷纤锌矿CdS的几何结构、能带结构、电子态密度及光学性质。通过计算分析可知,含Cd空位缺陷的CdS体系均为p型半导体,含S空位缺陷的CdS体系跃迁方式均由直接跃迁变为间接跃迁。Cd、S空位缺陷的CdS体系的态密度总能量降低。空位CdS体系相较于本征CdS体系的静介电常数均有提高,并随着空位浓度的增大而增大,Cd空位缺陷体系更为明显,极化能力得到显著提升。空位Cd的CdS体系相较于本征CdS体系在红外波段存在明显的吸收,空位S的CdS体系相较于本征CdS体系在可见光波段存在明显的吸收。