Probing the microenvironment of an oligo-（p-phenylene vinylene） derivative encapsulated in polymer-impregnated sol-gel silica matrix

Polymer-impregnated silica sol-gel composite materials are hosts for organics in advanced optics application. An oligo-phenylene vinylene derivative 4,4‘-(1,4-phenylene dithenylene)-bis-(N-methyl pyridinium iodide) (OPVD) was introduced to poly(hydroxyethyl methacrylate) (PHEMA)-impregnated silica composite film by the sol-gel process. By comparing the X-ray diffraction, UV-visible spectra, steady-state and time-resolved fluorescence spectra of OPVD in three solid matrices (PHEMA/silica composite film, pure PHEMA film, and pure silica film), the similar results of PHEMA/silica composite film and pure PHEMA film demonstrate that the OPVD is primarily surrounded by a PHEMA-like environment in the composite matrix. The model of such structure is presented, which is useful for further understanding and optimizing of properties of doped sol-gel materials.     

Preparation of narrow band gap V2O5/TiO2 composite films by micro-arc oxidation

V₂O₅/TiO₂ composite films were prepared on pure titanium substrates via micro-arc oxidation (MAO) in electrolytes consisting of NaVO₃. Their morphology and elements were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis. Phase composition and valence states of species in the films were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS) were also employed to evaluate the photophysical property of the films. The V₂O₅/TiO₂ composite films show a sheet-like morphology. Not only V₂O₅ phase appears in the films when the NaVO₃ concentration of the electrolyte is higher than 6.10 g/L and is loaded at the surface of anatase, but also V⁴⁺ is incorporated into the crystal lattice of anatase. In comparison with pure TiO₂ films the V₂O₅/TiO₂ composite films exhibit significantly narrow band gap energy. The film prepared in an electrolyte consisting of NaVO₃ with a concentration of 8.54 g/L exhibits the narrowest band gap energy, which is approximately 1.89 eV. The V₂O₅/TiO₂ composite films also have the significantly enhanced visible light photocatalytic activity. The film prepared in an electrolyte consisting of NaVO₃ with a concentration of 8.54 g/L exhibits the best photocatalytic activity and about 93% of rhodamine is degraded after 14 h visible light radiation.     

Hydrogen storage properties of MgH<Subscript>2</Subscript> co-catalyzed by LaH<Subscript>3</Subscript> and NbH

To improve the hydrogen storage properties of Mg-based alloys, a composite material of MgH₂ + 10wt%LaH₃ + 10wt%NbH was prepared by a mechanical milling method. The composite exhibited favorable hydrogen desorption properties, releasing 0.67wt% H₂ within 20 min at 548 K, which was ascribed to the co-catalytic effect of LaH₃ and NbH upon dehydriding of MgH₂. By contrast, pure MgH₂, an MgH₂ + 20wt%LaH₃ composite, and an MgH₂ + 20wt%NbH composite only released 0.1wt%, 0.28wt%, and 0.57wt% H₂, respectively, under the same conditions. Analyses by X-ray diffraction and scanning electron microscopy showed that the composite particle size was small. Energy-dispersive X-ray spectroscopic mapping demonstrated that La and Nb were distributed homogeneously in the matrix. Differential thermal analysis revealed that the dehydriding peak temperature of the MgH₂ + 10wt%LaH₃ + 10wt%NbH composite was 595.03 K, which was 94.26 K lower than that of pure MgH₂. The introduction of LaH₃ and NbH was beneficial to the hydrogen storage performance of MgH₂.     

Morphology controllable synthesis of Pd/CeO2–ZrO2 catalysts and its structure-activity relationship in three-way catalytic performance

CeO₂–ZrO₂ mixed oxides with controlled morphologies(i.e., nanorod, nano-polyhedral and disordered shape)were synthesized through either hydrothermal or coprecipitation method, and the corresponding supported Pd/CeO₂–ZrO₂ catalysts were also prepared by conventional impregnation. The obtained catalysts were subjected to systematic structural/physio-chemical characterizations as well as three-way catalytic performance evaluations.The results showed that ...     

Structure and transport studies on nanometer YBCO/PBCGO multilayers

We have fabricated M doped （M = Al, Co, Fe, Ga, Ni and Zn） PrBa2Cu3O7（PBCO）, i.e. PrBa2（CU1-xMx）3O7. The doping levels x are 0.05, 0.10, 0.15, and 0.20. X-ray data indicated no significant second phase for substituting Cu by Al, Co, Fe and Ga up to 20%. However impurity phases were detected for Ni and Zn substituted samples with doping levels equal to and higher than 15%. At 77 K the electrical resistivity of these compounds is orders in magnitude higher than that of PBCO. We also found that although the lattice parameters in the doped samples differ from PBCO, all samples remain orthorhombic. The lattice parameters of the doped sample are very close to those of YBa2CU3O7-δ （YBCO） and PBCO. For this reason these compounds are better materials to be used as the I-layer for YBCO SIS junctions. Results of structural and transport studies on 2000 A thick PrBa2[Cu0.80G0.2]3O7 （PBCGO） and YBCO/PBCGO multilayers are presented in this paper.     

Tuning the magnetic anisotropy in LSMO manganite films through non-magnetic nanoparticles

We report the observation of anomalous magnetic anisotropy driven by nonmagnetic ZrO2 nanoparticles in epitaxial La2/3Sr1/3MnO (LSMO) films grown on LaAlO3 (LAO) substrates. The compressive epitaxial strain imposed by the lattice mismatch of substrate and film is tuned by the density of ZrO2 nanoparticles embedded in the film matrix and affects the magnetic anisotropy as well as the magnetotransport properties. Epitaxial 54 nm thick LSMO thin films with different concentrations of ZrO2 nanoparticles demonstrate anisotropic hysteresis loops concomitant with anisotropic magnetotresistance behavior. The biaxial epitaxial strain, induced by the substrate/film lattice parameter mismatch is partially relaxed by increasing the density of precipitates and they serve as a tuning parameter for the strain state. We interpret our results by a strain-induced interplay of impurity scattering, weak localization and magnetic domain structure.     

Highly sensitive ZnO nanoparticles-loaded In2O3 hollow microsphere for detecting ppb-level NO2 at low working temperature

This paper presents a NO₂ sensor operating at low temperature, which was fabricated by ZnO nanoparticles-loaded In₂O₃ hollow microspheres composites. SEM, XRD, XPS and HRTEM were executed to determine the morphology and microstructure of ZnO–In₂O₃. The sensing performance of pure In₂O₃ and ZnO–In₂O₃ composite sensors was tested. The NO₂ sensing properties of the composite were greatly improved in contrast with the pure In₂O₃ sensor at the optimized operating temperature (75 °C). ZnO–In₂O₃ composite sensor exhibited an obviously higher response (805.2 for 100 ppb NO₂) than that of the pure In₂O₃ sensor (14 for 100 ppb NO₂). In particular, the response/recovery rate of ZnO–In₂O₃ composite sensor was greatly improved in contrast with the pure In₂O₃ sensor. The n-n heterojunctions created at ZnO–In₂O₃ interfaces improved the sensing performance.     

Preparation and magnetic properties of CoFe2O4/TiO2 composite films

Using （Ti（OC4H9）4） and metal chlorates as starting materials, CoFe2O4/TiO2 composite films were prepared by sol-gel method. The effects of heat treatment temperature and pH of the precursor on microstructure and magnetic properties were studied. The phase structure of the samples was examined by X-ray diffraction. The microstructure was examined by scanning electron microscope, atomic force microscope and polarized microscope. The magnetic property was measured by vibrating sample magnetometer. The results show that the crystals of different phases grow up independently. CoFe2O4 is uniformly embedded into the TiO2 matrix in the prepared composite films, and the growth of composite films is dependent on the heat treatment temperatures and PH of the precursor. The average size of CoFe2O4 crystal is 19 nm in Nanocomposite film prepared when the heat treatment temperature is 800℃ and the pH of the precursor is between 2 and 3. The magnetism of the composite films is enhanced as the heat treatment temperature increases.     

CeO2包覆TiO2的XPS研究

Redox capacity of CeO₂ coating TiO₂ is discussed.It is showed that CeO₂ is easy to be reduced and can be re-oxidized while expoursing O@fs(50)2@fs(100).Due to Ti⁴⁺ mixed in the CeO₂ lattice,the activation energy decrease,which attributed to oxygen vacancy migration.     

尿素辅助模板法合成介孔氮掺杂CeO2及其CO2捕获应用研究

以硝酸铈为前驱物,以尿素为助剂,采用一种简单的模板法合成了介孔氮掺杂CeO₂材料.利用X射线衍射仪(XRD)、吸附-脱附仪(BET)、透射电子显微镜(TEM)和傅里叶变换红外光谱(FT-IR)等设备对合成材料进行表征.多种测试结果证明:试验得到的纳米材料具有均一的介孔结构和较高的比表面积(124.8 m²·g^-1)并掺杂了氮元素.同时,测定了介孔CeO₂材料对于CO₂的吸附性能,并研究了氮掺杂对CeO₂材料的CO₂吸附性能的影响.结果表明:相比未掺杂氮的介孔CeO₂,氮掺杂的介孔CeO₂具有更好的CO₂吸附性能和循环吸附脱附性能.     

CuO/CeO_2空心球的制备及其对CO的氧化性能研究(英文)

报道了一种利用PS模板制备CuO负载CeO_2空心球的简便方法。用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射(XRD)、N_2吸附-脱吸等温线和X射线光电子能谱(XPS)对CuO/CeO_2空心球的结构特征进行了表征。为了评价CuO/CeO_2空心球之间的催化性能差异,采用工业CeO_2和CeO_2空心球,H_2温度程序还原(H_2-TPR)和CO氧化试验。结果表明,合成的样品形貌好,比表面积大,纯度高。H_2-TPR分析表明,CuO/CeO_2空心球的还原性具有多种表面活性物。CuO掺杂的CeO_2空心球表现出比CeO_2空心球和商业CeO_2在CO氧化中的更好的性能,因为铜通过氧缺陷的增加和协同效应有效增强了样品对CO催化活性。     

羟基磷灰石/钛网状复合材料的制备及其性能

以Ca(OH)2和H3PO4为反应物,通过溶胶-凝胶法制备了羟基磷灰石(HA)粉体;用机械混合法制备了TiH2包覆HA的粉体;用热压法制备了纯HA陶瓷材料及HA/Ti复合材料.XRD相分析结果表明:通过溶胶-凝胶法制备的HA粉体,经过900℃煅烧2 h后,粉体的主晶相为HA,有少量的CaO;HA/TiH2包覆粉末经1 050℃热压后,复合材料中的主要相是HA和Ti,同时出现了Ca2P2O7和Ca3(PO4)2相.1 050℃热压的HA/25%Ti(体积分数)复合材料的断裂韧性为2.4 MPa.m-1/2,抗弯强度为54 MPa,均高于纯HA材料.显微组织的观察表明金属钛在材料中呈网状分布,网状...     

热处理温度对溶胶-凝胶法制备的Ce_(0.97)Co_(0.03)O_2薄膜结构和光学性能的影响

采用溶胶-凝胶法,在Si(100)衬底上制备了3%Co掺杂CeO2薄膜,研究了不同热处理温度对Ce0.97Co0.03O2薄膜结构和光学性质的影响。X射线衍射(XRD)表明,3%Co掺杂CeO2薄膜为多晶薄膜,且未破坏CeO2原有的结构,随着退火温度的升高,晶粒尺寸逐渐增大。椭偏光谱法研究表明,Ce0.97Co0.03O2薄膜的光学常数(折射率n、消光系数k)随着退火温度增加而增大,光学带隙Eg随退火温度增加而减小,这是薄膜结构随退火温度增加发生变化所致。     

Silicon-phthalocyanine bonding with SiO2 matrix and its strong optical limiting effects

Silicon-phthalocyanine (SiPc) is chemically bonded to 3-aminopropitriethoxysilane (NH₂(CH₂)₃Si(OC₂H₅)₃, KH550) by the nucleophilic substituted reaction between the active chlorine of silicon dichlorine phthalocyanine (SiPcCl₂) and amino-group of KH550. The reacted product is hybridized with 3-glycidoxypropitrimethoxysilane (CH₂OCHCH₂O(CH₂)₃Si(OCH₃)₃, KH560) with sol-gel processing to form sol-gel inorganic material with good physical-chemical and optical properties. Due to tethering SiPc to the network, the aggregation of SiPc is effectively prevented in sol-gel derived matrix, and the doping concentration of SiPc in the form of monomer in the matrix is greatly enhanced. The cross-linkage of SiPcCl₂ and KH550 is estimated and confirmed with FT-IR spectra. The optical limiting effects (OLE) of the gel with different content of SiPc are investigated with a frequency double Q-switched Nd₃₊:YAG laser of 8 nsec. pulse.     

Fabrication,microstructure, and optical properties of nanocrystalline transparent LAST glass ceramics containing CeO2

In the present research, the effect of CeO2 dopant on the fabrication of transparent lithium aluminosilicate titanate （LAST） glass ceramics was investigated. Nanocrystallineβ-quartz solid solution （s.s.） was observed to be the main phase crystallized in this system. Com-parable refractive indices of the glassy matrix andβ-quartz s.s., as well as the incorporation of very fine grains size were determined as the main reasons for retaining the transparency of the glass ceramics. CeO2 was introduced as a suitable optical agent, playing a role as a network modifier in the glass ceramics, because it does not accelerate the growth process and retards the extended growth of crystals. Optical investi-gations indicate that the Fermi energy level, direct and indirect band gaps, and Urbach energy decrease with increasing nanocrystal content in the glassy matrix of specimens, which can be related to the expansion of conduction band, the enhancement of ionic bonds in the crystal lat-tice, and the enhancement of structural arrangement degree, respectively.     

Synergistic effect between ceria and tungsten oxide on WO3–CeO2–TiO2 catalysts for NH3-SCR reaction

WO3–CeO2–TiO2 catalysts for NO (nitrogen monoxide) reduction by ammonia were prepared by a sol–gel method. The catalysts were characterized by BET, XRD, Raman, NH3/NO adsorption and H2-TPR to investigate the relationships among the catalyst composition, structure, redox property, acidity and deNOx activity. WO3–CeO2–TiO2 catalysts show a high activity in a broad temperature range of 200–480 1C. The low-temperature activity of catalysts is sensitive to the catalyst composition especially under low-O2-content atmospheres. It may be related to the synergistic effect between CeOx and WOx in the catalysts. On one hand, the interaction between ceria and tungsten oxide promotes the activation of gaseous oxygen to compensate the lattice oxygen consumed in NH3-SCR (selective catalytic reduction) reaction at low temperatures. Meanwhile, the Br?nsted acid sites mainly arise from tungsten oxides, Lewis acid sites mainly arise from ceria. Both of the Br?nsted and Lewis acid sites facilitate the adsorption of NH3 on catalysts and improve the stability of the adsorbed ammonia species, which are beneficial to the NH3-SCR reaction.     

P3HT和Spiro-OMeTAD共混物作为光活性层的杂化太阳电池性能

为降低电荷复合率,提高杂化太阳电池的性能,将P3HT与Spiro-OMeTAD共混后的混合物作为光活性层和空穴传输层,旋涂在Sb_2S_3纳米粒子敏化的TiO_2纳米棒(TiO_2NR/Sb_2S_3)复合膜上,制备成杂化太阳电池。通过SEM、紫外可见吸收光谱、XRD、电化学阻抗图谱、稳态荧光光谱、J-V曲线等手段,对杂化太阳电池的微观结构、光电转换特性进行了表征和测试。结果表明:P3HT与Spiro-OMeTAD共混物比例为15 mg/1 mL时,得到结构为FTO/TiO_2NR/Sb_2S_3/P3HT:Spiro-OMeTAD/Ag杂化太阳电池的电荷负荷率低,电子生命长,能量转换效率达到了4.57%。所制备的杂化太阳电池性能优良,具有良好的应用前景。     

Preparation of graphene and TiO2 layer by layer composite with highly photocatalytic efficiency

A process for fabricating graphene and TiO₂ layer by layer composite was introduced to improve the photocatalytic activity by controlling the layers, thickness and the mass ratio between graphene and TiO₂. The graphene oxide (GO) was synthesized from natural graphite powder by the modified Hummers method. Large-area uniform GO and TiO₂ thin films were made by a spin-coating process in turn. After exposure of the TiO₂/GO multilayer film to UV light irradiation which allows the reduction of GO to graphene, a novel photocatalytic structure as graphene and TiO₂ layer by layer composite was synthesized. The cross-sectional SEM image showed that a clear layer by layer microstructure with a single layer thickness of graphene or TiO₂ was in the range of about 50 nm. The total thickness of the film was around 5 μm which was varied according to the layer number of spin coating process. Raman spectra revealed that significant structural changes occurred through UV light irradiation. Photodegradation for methylene blue (MB) exhibited that the layer by layer composite is of higher photocatalytic activity than the pure TiO₂ layer.     

Li5La3Ta2O12/Al基高阻尼复合材料的制备和阻尼性能

采用粉末冶金法制备Li₅La₃Ta₂O₁₂/Al基陶瓷复合材料,并评价其阻尼性能、硬度和屈服强度.结果表明,复合材料的室温阻尼和力学性能较纯Al具有显著提高.当陶瓷颗粒质量分数为20%时,复合材料的室温内耗值可达0.010, 比相同温度范围内Al的内耗高约1个量级,对应的屈服强度和硬度值分别比Al提高约43%和28%.     

MoS2/g-C3N4复合光催化剂的构建及其可见光催化性能研究

本研究通过水热合成法和超声法成功构建MoS₂/g-C₃N₄复合型光催化剂。通过X射线粉末衍射（XRD）、扫描电子显微镜（SEM）、红外光谱（IR）以及紫外-可见吸收光谱（UV-Vis）表征技术对复合型催化剂的物理化学特性进行分析。以光催化降解罗丹明B（RhB）为探针反应,探究可见光下不同质量比的MoS₂/g-C₃N₄复合型光催化剂对RhB光催化降解性能的影响。实验结果表明,当MoS₂负载量为30%,光催化降解80 min时,10 mg/L的RhB溶液的降解率为96.7%。MoS₂/g-C₃N₄复合催化剂相比于纯的g-C₃N₄,MoS₂降解RhB的效果有显著地提高。光催化降解性能的提升归因于两半导体间MoS₂和g-C₃N₄异质结界面构筑,有效地抑制光生电子（e^-）和空穴（h⁺）的复合,从而提高复合型光催化剂MoS₂/g-C₃N₄的光催化性能。