S型异质结光催化剂ZnFe2O4/WO3的构筑及光催化还原CO2性能

通过在WO₃纳米片表面负载ZnFe₂O₄纳米颗粒,构建了一系列S型异质结光催化剂ZnFe₂O₄/WO₃,并研究了其光催化CO₂还原性能。在没有助催化剂和牺牲剂的条件下,所制备的ZnFe₂O₄/WO₃复合材料可对CO₂与水蒸汽进行光催化反应。优化后的材料光照5 h后CO₂还原产物CO和CH₄的产量分别为7.87和4.88 μmol·g^-1。相对于单相组分,CO和CH₄的产量明显提高。光催化活性的提高,归因于ZnFe₂O₄和WO₃异质结的形成以及光生载流子的S型电荷传输模式。     

WxC-MCM-48催化剂的合成、表征及加氢脱硫催化性能

以正硅酸乙酯(TEOS)为硅源，十六烷基三甲基溴化铵(CTAB)为表面活性剂，仲钨酸铵为钨源，采用水热晶化法一步合成了不同钨含量(以Si、W物质的量比n_Si/n_W表示)的WO₃-MCM-48，然后经甲烷/氢气(V/V=1/4)混和气体程序升温还原碳化(TPC)，制备出了W_xC-MCM-48(x=1、2)催化剂，采用XRD、N₂吸附-脱附和NH₃-TPD对样品的结构进行了表征，用噻吩作为模型化合物，对W_xC-MCM-48催化剂的加氢脱硫催化活性进行了评价。结果表明，在一定钨含量的条件下，WO₃-MCM-48和W_xC-MCM-48样品仍然保持MCM-48的三维立方有序介孔结构，n_Si/n_W=30～15时，碳化钨的物相为W₂C；n_Si/n_W=7.5时，碳化钨为W₂C和WC物相，W_xC-MCM-48催化剂表现出了良好的加氢脱硫催化性能。     

S型异质结光催化剂ZnFe2O4/WO3的构筑及光催化还原CO2性能

通过在WO₃纳米片表面负载ZnFe₂O₄纳米颗粒,构建了一系列S型异质结光催化剂ZnFe₂O₄/WO₃,并研究了其光催化CO₂还原性能。在没有助催化剂和牺牲剂的条件下,所制备的ZnFe₂O₄/WO₃复合材料可对CO₂与水蒸汽进行光催化反应。优化后的材料光照5 h后CO₂还原产物CO和CH₄的产量分别为7.87和4.88 μmol·g^-1。相对于单相组分,CO和CH₄的产量明显提高。光催化活性的提高,归因于ZnFe₂O₄和WO₃异质结的形成以及光生载流子的S型电荷传输模式。     

花状TiO2分级结构的可控合成与其光催化性能

采用水热法可控合成了花状TiO₂分级结构材料,运用扫描电镜、透射电镜、X射线衍射、N₂物理吸附-脱附等手段,对其进行了表征,系统研究了NaOH用量、H₂O₂浓度、HNO₃浓度、反应温度及时间等因素对所得样品形貌的影响,并评价了它们的光催化性能.结果表明,花状TiO₂分级结构为锐钛矿相,颗粒大小均一;随制备条件的变化,构成花状TiO₂分级结构的基元结构分别为纳米线、纳米片,纳米线直径约25nm,纳米片厚度不足10nm;该样品具有较高的比表面积,表现出良好的单次光催化活性与重复使用性能.     

氧化铟八面体、纳米带、锯齿状纳米线和纳米链的可控合成

在N₂/H₂O混合气流中将硅片上金覆盖的金属铟颗粒加热到800 ℃制备出了不同形貌的In₂O₃纳米结构, 在距铟源不同距离处依次得到In₂O₃的八面体、纳米带、锯齿状纳米线和纳米链. 采用拉曼光谱、扫描电镜、X射线衍射和透射电镜对产物进行了表征分析. 结果表明, 八面体、纳米带、锯齿状纳米线和纳米链均为立方相单晶结构的In₂O₃. 基于气-固和气-液-固生长机理详细分析了八面体、纳米带、锯齿状纳米线和纳米链的生长过程, 提出了不同形貌In₂O₃纳米结构的生长模式.     

以氨基化的聚苯乙烯微球为模板制备电致变色性能优良的单层有序多孔PBTB薄膜

以氯化钨和氧化石墨烯(GO)为原料,乙醇为溶剂,一步合成了WO₃纳米棒/石墨烯纳米复合材料(WO₃/RGO). 将WO₃/RGO纳米复合材料用于锂离子电池负极,并通过充放电测试、循环伏安(CV)和电化学阻抗谱(EIS)技术综合考察了该材料的储锂性能. 结果显示,在0.1C (1C=638 mA·g^-1)倍率下,复合物的首次放电比容量达到761.4 mAh·g^-1,100次循环后可逆容量仍保持在635 mAh·g^-1,保持率为83.4%. 即使在5C倍率下容量仍高达460 mAh·g^-1. 由此说明,WO₃/RGO纳米复合物具有优异的循环稳定性及倍率性能,可望用于高性能锂离子电池.     

不同形貌纳米CoWO4的水热法制备及气敏性能

以Co（NO₃）₂·6H₂O、Na₂WO₄·2H₂O为主要原料,去离子水为溶剂,利用水热法在不同条件下制备了一系列的纳米CoWO₄,用XRD、TEM和比表面分析仪对产品的物相、形貌和比表面积进行了表征。较系统地探讨了水热条件（反应混合物pH值、反应时间、反应温度等）对产物物相和形貌的影响,并研究了不同形貌产品对甲醛、乙醇、氨气、苯和丙酮等的敏感性能。结果表明：水热条件对产品的物相和形貌有影响,在不同水热条件下,可成功制备CoWO₄纳米颗粒、纳米立方体及纳米棒;以纳米颗粒、纳米立方体及纳米棒样品制成的气敏元件对被试气体有不同程度的响应,其中以纳米颗粒为基的元件在210℃对1000μL·L^-1NH₃灵敏度为3.3。     

In2O3敏化ZnO纳米棒阵列的性能及其光电催化活性

以掺氟SnO₂ (FTO)导电玻璃为基底, 采用水热法制备了ZnO纳米棒阵列. 通过In(NO₃)₃水溶液水洗的方法, 合成了In₂O₃敏化ZnO纳米棒阵列光催化剂. 采用场发射扫描电子显微镜(FESEM), X射线能谱(EDX), X射线衍射(XRD)及紫外-可见漫反射光谱(UV-Vis DRS)对样品的形貌、结构、组成、晶相等进行一系列的表征. 以罗丹明B (RhB)为目标降解物, 探究了In₂O₃敏化ZnO 纳米棒阵列光电催化活性. 采用场诱导表面光伏技术(FISPV)研究了不同含量的In₂O₃敏化ZnO纳米棒阵列在光照射下的光生电荷行为. 结合电化学工作站检测不同样品的光电流, 随着In₂O₃敏化量的改变, 光电流和开路电压也随之改变. 并探讨了In₂O₃敏化ZnO纳米棒阵列光生电荷行为与光电催化活性之间的关系. 结果表明, 适量In₂O₃敏化的ZnO光催化剂在可见光下2 h内对罗丹明B的降解效率达到95%, 是单纯ZnO纳米棒阵列的2.4倍.     

表面活性剂辅助合成CdWO4纳米棒和纳米线

以Na₂WO₄•2H₂O和CdCl₂ 为主要原料, 分别在十六烷基三甲基溴化铵(CTAB)和十二烷基苯磺酸钠(SDBS)表面活性剂中, 在180 ℃反应16 h, 水热制备了CdWO₄纳米棒和纳米线. 利用X射线粉末衍射(XRD)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)等手段对产物进行了表征, 并对其在室温下的发光特性进行了测定. 实验结果表明: 产物均为具有单斜结构的单相CdWO₄. 其中CdWO₄纳米棒具有单晶属性, 平均粒径约为63 nm, 长度近1 µm; 而CdWO₄纳米线具有多晶特性, 平均粒径约为12 nm, 长度达十几微米. 当激发波长为253 nm时均有460 nm强的发射峰, 其中CdWO₄单晶纳米棒的发光强度大于CdWO₄多晶纳米线. 分别对CdWO₄纳米棒和纳米线形成的可能机理进行了初步分析.     

表面活性剂辅助合成CdWO4纳米棒和纳米线

以Na₂WO₄•2H₂O和CdCl₂ 为主要原料, 分别在十六烷基三甲基溴化铵(CTAB)和十二烷基苯磺酸钠(SDBS)表面活性剂中, 在180 ℃反应16 h, 水热制备了CdWO₄纳米棒和纳米线. 利用X射线粉末衍射(XRD)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)等手段对产物进行了表征, 并对其在室温下的发光特性进行了测定. 实验结果表明: 产物均为具有单斜结构的单相CdWO₄. 其中CdWO₄纳米棒具有单晶属性, 平均粒径约为63 nm, 长度近1 µm; 而CdWO₄纳米线具有多晶特性, 平均粒径约为12 nm, 长度达十几微米. 当激发波长为253 nm时均有460 nm强的发射峰, 其中CdWO₄单晶纳米棒的发光强度大于CdWO₄多晶纳米线. 分别对CdWO₄纳米棒和纳米线形成的可能机理进行了初步分析.     

氧化钨纳米棒团簇的制备及电催化性能

以氯化钨为前驱体,通过溶剂热法制备了WO₃和W₁₈O₄₉并将其应用在染料敏化太阳能电池(dye-sensitized solar cells,DSSCs)和电解水析氢反应(hydrogen evolution reaction,HER)中。通过X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)和透射电子显微镜(TEM)对WO₃和W₁₈O₄₉的结构和形貌进行表征。结果表明：WO₃和W₁₈O₄₉均为单斜相,其形貌表现为定向排列的纳米棒组成的团簇。X射线光电子能谱(XPS)和电子顺磁共振(EPR)表明W₁₈O₄₉中含有丰富的氧空位。基于氧空位优异的电化学特性,W₁₈O₄₉对电极组装的DSSC获得了7.41%的光电能量转换效率(power conversion efficiency,PCE),高于WO     

Study on mechanism of hydrogen adsorption on WO3, W20O58, and W18O49

The density functional theory (DFT) calculation of hydrogen adsorption on tungsten oxides and calculation of the crystal structure of WO₃, W₂₀O₅₈, and W₁₈O₄₉ were performed_. These calculations suggest that the length of W-O bonds in WO₃ are 1.913 Å, the length of 66% W-O bonds in W₂₀O₅₈ is 1.8 to 1.9 Å, and the length of 43.48% W-O bonds in W₁₈O₄₉ is longer than 2.0 Å. The hydrate (WO₂[OH]₂), as an autocatalyst in the hydrogen reduction process, was found in the particular adsorption configuration of W₁₈O₄₉. The WO₃ and W₂₀O₅₈ were completely reduced within 40 to 60 minutes at a temperature of 1000°C and at a hydrogen flow rate of 200 mL/min, while W₁₈O₄₉ was completely reduced within 20 to 40 minutes. The phase composition and micromorphology of raw material and production were studied by both X-ray diffraction analysis (XRD) and FE-SEM technology. The differences of the mechanism of hydrogen adsorption on WO₃, W₂₀O₅₈, and W₁₈O₄₉ were explored based on the density functional theory calculation and the hydrogen reduction experiments.     

一维纳米材料Cs0.2WO3和W18O49长度与红外吸收关联性的Mie散射理论推导及实验验证

研究表明二元、三元钨基氧化物的红外吸收性能具有尺寸和形貌依赖性,但还没有普适性的物理学机理及计算方法。本工作基于Mie散射理论,推导了一维材料的长度与光吸收性能之间的关系,通过理论推导计算和实验验证,探究了纳米钨基氧化物的红外吸收性能与颗粒长度的关联性。首先,基于Mie散射理论的推演和计算,揭示了增加纳米Cs_(0.2)WO_3和W_(18)O_(49)材料长度可适度提高其近红外吸收性能的规律。其次,测试了合成的不同长度Cs_(0.2)WO_3纳米棒和W_(18)O_(49)纳米线的红外吸收性能,结果与理论计算及模拟相吻合。其中在2 500～20 000 nm波长范围内Cs_(0.2)WO_3纳米棒和W_(18)O_(49)纳米线随长度的变化趋势不同,Cs_(0.2)WO_3纳米棒的红外吸收性能随长度的增加而增加,而W_(18)O_(49)纳米线的红外吸收性能随长度的增加而减弱。Cs_(0.2)WO_3纳米棒和W_(18)0O_9纳米线的光热效应均随长度的增加而增加,增幅分别达18.5%和12.7%,再次验证了长度效应。     

Nonlinear current-voltage characteristics of WO3-x nano-/micro-rods

A series of crystalline tungsten oxide nano-/micro-rods with different compositions of WO₃, WO_2.90, W₁₉O₅₅ (WO_2.89) and W₁₈O₄₉ (WO_2.72) but identical morphology feature were first prepared. Then, various nanoscaled electrical devices were fabricated from them by micro-fabrication through a focused ion beam technique. Interestingly, the devices from the oxygen-deficient WO_3-x display significantly nonlinear current-voltage characteristics. The calculated nonlinear coefficients of the WO_2.90, WO_2.83, and WO_2.72 varistors are 2.52, 3.32 and 4.91, respectively. The breakdown voltage of the WO_2.90, WO_2.83, and WO_2.72 varistors are 1.93, 1.28 and 0.93 V, respectively. Such WO_3-x nano-varistors might be promising for low-voltage electrical/electronic devices.     

Electron microscopy studies of W18O49. 1. Crystals formed by gaseous reduction of WO3

W₁₈O₄₉ samples were prepared by reduction of WO₃ crystals at various temperatures (at about 1170, 1270, and 1370K) by equilibration with a gaseous buffer of controlled oxygen pressure. The samples were studied by high-resolution electron microscopy. The results show that an amorphous phase is an intermediary step in the formation of W₁₈O₄₉. Defects are very rarely observed in as-reduced W₁₈O₄₉, which differs in this respect from other tungsten oxides. Apart from twinning, however, three types of extended defects have been observed occasionally, and these are interpreted and discussed.     

水热法合成双金属多元型的Mo1.8W16.2O49纳米棒

近年来,纳米材料在电子学[1]、光电子学[2]和存储元件[3]等技术的发展方面起到至关重要的作用。在纳米材料的合成中,过渡金属氧化物的合成越来越受到人们的重视[4,5]。一维过渡金属氧化物纳米材料具有特殊的光学、磁学和电学特性。其中,一维氧化钨(WO3-x,0≤x<3)纳米材料具有很     

Zum chemischen Transport der Wolframoxide WO2 und W18O49 mit HgI2. Experimente und Modellrechnungen

On the Chemical Transport of Tungsten Oxides WO₂ and W₁₈O₄₉ with Hgl₂. Experiments and Calculations Transport experiments with WO₂ or W + WO₂ or WO₂ + W₁₈O₄₉ show that HgI₂ is a transport agent as suitable as I₂. We observed transport rates up to 47 mg/h. We investigated the dependence of the transport rate on the concentration of the transport agent n°(HgI₂) as well as on the temperature. We also investigated the time dependence of the transport rates during transport experiments on a “transport balance”. Starting with WO₂ + W₁₈O₄₉, WO₂ is transported before W₁₈O₄₉. Thermodynamic calculations show that transport of W₁₈O₄₉ is understandable if the presence of small amounts of H₂O from the quartz glass wall are taken into consideration, while transport of WO₂ is possible with HgI₂ in the presence of H₂O as well as in absence of H₂O. is the most important reaction for the transport of WO₂.     

The APCVD of tungsten oxide thin films from reaction of WCl6 with ethanol and results on their gas-sensing properties

The APCVD reaction of WCl₆ with ethanol was examined to deposit tungsten oxide on gas sensor substrates. Deposited films, which were WO_3−x, displayed a different morphology than those seen previously for CVD tungsten oxide. The gas-sensing properties of the deposited films were examined.     

Morphology modulated growth of bismuth tungsten oxide nanocrystals

Two kinds of bismuth tungsten oxide nanocrystals were prepared by microwave hydrothermal method. The morphology modulation of nanocrystals synthesized with precursor suspension's pH varied from 0.25 (strong acid) to 10.05 (base) was studied. The 3D flower like aggregation of Bi₂WO₆ nanoflakes was synthesized in acid precursor suspension and the nanooctahedron crystals of Bi_3.84W_0.16O_6.24 were synthesized in alkalescent precursor. The dominant crystal is changed from Bi₂WO₆ to Bi_3.84W_0.16O_6.24 when the precursor suspension changes from acid to alkalescence. The growth mechanisms of Bi₂WO₆ and Bi_3.84W_0.16O_6.24 were attributed to the different solubility of WO₄²⁻ and [Bi₂O₂]²⁺ in precursor suspensions with various pH. For the decomposition of Rhodamine B (RhB) under visible light irradiation (λ>400 nm), different morphology of Bi₂WO₆ crystal samples obtained by microwavesolvothermal process showed different photocatalytic activity.     

From Cluster to Cluster: Structural Transformation Reactions Among Tungsten Chloride Clusters

Reactions between tungsten halides are discussed along the series of compounds WCl₆ → WCl₄ → W₆Cl₁₂ ↔ W₆Cl₁₈ → [W₆CCl₁₈]ⁿ⁻ ← [W₃Cl₁₃]^u−, focusing on the two closely related tungsten chloride compounds whose structures compromise the well-known octahedro W₆Cl₁₈ cluster and the carbon-centered triprismo W₆CCl₁₈ cluster. Both clusters can be regarded as being built by merging two trigonal [W₃Cl₁₃]^u− units in different ways. Syntheses, structural transformation reactions, and concepts regarding electronic structures are reported.