氧化铟纳米纤维的制备及其甲醛气敏性能

采用静电纺丝法和随后的热处理过程制备了新颖的氧化铟纳米纤维材料. 利用扫描电子显微镜,透射电子显微镜,X射线衍射等表征手段对该材料形貌和晶体结构进行表征. 结果表明,所得到的纳米纤维材料的直径约为250 nm~300 nm. 这些纳米纤维由氧化铟纳米颗粒组成,而且其颗粒尺寸均一. 将这种纳米纤维材料制备成气敏传感器,研究表明基于该敏感材料的传感器对甲醛具有优异的气敏性能. 氧化铟纳米纤维传感器具有较低的最佳工作温度 200 ℃,并且对低体积浓度为百万分之五的甲醛气体具有2.1的灵敏度响应值. 在探讨甲醛的气敏机理的过程中,认为氧化铟纳米纤维的一维结构、甲醛的高还原性及敏感材料表面吸附氧促使了该材料对甲醛的优异的气敏性能. 此外,通过对传感器的选择性及稳定性测试,传感器对甲醛具有非常好的选择性和稳定性,这为制备高性能的甲醛传感器开拓了一种优异的气敏材料.     

基于双金属MOFs 制备Co3O4/In2O3 复合物及其气敏性能的研究

以硝酸铟(In(NO₃)₃·xH₂O)、对苯二甲酸(H₂BDC)、六水合硝酸钴(Co(NO₃)· 6H₂O) 为原料, 首先采用一锅油浴法合成了含有Co²⁺ 的铟基金属有机框架材料(MOFs) Co²⁺/CPP-3(In) 材料, 然后在450 ℃ 下焙烧制备Co₃O₄/In₂O₃ 复合物气敏材料, 将Co₃O₄/In₂O₃ 复合物的粉体制作成传感器, 并对其气敏性能进行研究。利用扫描电子显微镜和X 射线衍射仪(XRD) 对双金属MOFs Co²⁺/CPP-3(In) 材料和Co₃O₄/In₂O₃ 复合物进行表征, 采用静态配气法测试其气敏性能。结果表明, Co₃O₄/In₂O₃(n_Co : n_In = 0.4 : 1) 样品的形貌保留了其MOFs 前驱体的棒状结构, 棱柱形框架更为突出, 表面呈凹陷状, 棒体中间粗两边细, 六角截面和棒体均布满了孔洞。结合EDX 和XRD 表征结果, Co²⁺/CPP-3(In) MOFs 前驱体完全转化成Co₃O₄/In₂O₃ 复合物; Co₃O₄/In₂O₃(n_Co : n_In = 0.4 : 1) 复合物在 70 ℃ 下对5×10^-6 H₂S 的气敏性能最优, 响应值达到153, 是同条件下纯备In₂O₃对H₂S 响应值的5 倍, 并且有较好的重复性、选择性和稳定性。     

纳米片状WO3的水热合成及其NO2气敏性能

以钨酸钠(Na_2WO_4·2H_2O)为原料,采用水热法制备出纳米片状WO_3,并用X射线衍射仪和扫描电镜对产物的组成及形貌进行表征。将该纳米材料制作成气敏元件,对不同浓度的NO_2气体进行测试。结果表明,所制备的传感器对低浓度的NO_2气体有良好的灵敏度,响应和恢复时间分别只需5 s和130 s。     

基于铜基金属有机框架材料的CuO气体传感器

以硝酸铜[Cu(NO_3)_2·3H_2O]、均苯三甲酸(H_3BTC)为原料,通过水热法制备铜基金属有机框架(metal organic framework, MOF)材料—Cu_3(BTC)_2·3H_2O (HKUST-1),并以此为自牺牲模版,通过煅烧得到八面体形貌的CuO,改变HKUST-1反应温度以及煅烧温度得到不同反应条件下的产物。利用扫描电镜和X射线衍射对前驱体HKUST-1和CuO进行表征。将CuO粉体制成气体传感器,通过静态配气法对传感器进行气敏测试并探究其气敏性能。结果表明,在HKUST-1反应温度为85℃、煅烧温度为500℃时,制备得到的粒径在5μm左右的八面体CuO对硫化氢气体有较好的气敏性能。     

介孔氧化铟纳米粒子的制备及其气敏性质

以介孔氧化硅KIT-6为硬模板制备了介孔氧化铟纳米粒子,并对其进行了X射线粉末衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）、氮气物理吸附分析。介孔氧化铟纳米粒子具有高的结晶度和有序介观结构,其尺寸为100 nm左右,比表面积为82 m2/g,孔径为4.5 nm左右,孔体积为0.42cm3/g。气敏性能测试结果表明介孔氧化铟纳米粒子对乙醇具有较好的敏感度,优于体相的氧化铟颗粒,在乙醇气体检测方面有潜在的应用。     

WO3纳米粉体的制备及其气敏性能分析

以PEG-400为分散剂制得WO3纳米粉体,用粉末X-射线衍射仪(XRD)和透射电镜(TEM)对产物的物相和形貌进行了表征。结果显示:产物为球形颗粒,600℃下热处理2h颗粒平均粒径为80nm。将粉体制成旁热式气敏元件,气敏性能测试结果表明:该WO3纳米粉体对三甲胺具有较高的灵敏度和选择性。600℃下热处理2h材料气敏性最好,在240℃(最佳工作温度)下对体积分数为1×10-8的三甲胺灵敏度可达到3.2。     

SnO2气敏元件敏感性能的研究

为了探讨具有优良性能的SnO2气敏元件的研制方法,依据半导体晶界气敏理论．以SnO2为基体材料,采用烧结型工艺和溶胶一凝胶方法制备出了气敏器件,并对该元件的气敏特性进行了测试,结果表明,采用溶胶一凝胶方法制备的气敏元件具有较高的灵敏度和低电阻等特点,对氢气响应时间可以达到5s.     

Al2O3(Pt)修饰SnO2气体传感器的气敏性能

采用共溶溶胶凝胶法及半透膜渗析技术,合成SnO_2纳米粉体．采用旁热式结构,制成了Al_2O_3(Pt)修饰SnO_2双层膜的气体传感器．通过TEM、SEM分析方法分别对SnO_2粉体、敏感膜以及Al_2O_3(掺质量分数3%Pt)表面催化层的表面形貌进行观察和表征．实验结果表明,Al_2O_3(掺质量分数3%Pt)修饰SnO_2双层膜气体传感器对甲烷有好的选择性和较高的灵敏度。在φ(CH_4)= 5×10~(-3)时灵敏度最高可达到5以上．     

g-C3N4@ZIF-8@MoS2复合材料的制备及光催化性能研究

通过室温下自组装法制备g-C3N4二元复合物,再用水热法制备花状的g-C3N4@ZIF-8@MoS2复合光催化剂.运用X射线衍射仪、扫描电子显微镜以及能谱仪对g-C3N4@ZIF-8@MoS2复合材料进行结构表征,并通过光催化降解亚甲基蓝考察了其光催化性能.结果表明,g-C3N4@ZIF-8@MoS2复合材料在水中具备...     

掺镍多孔纳米SnO2材料的制备及其气敏性能

以SnCl4·5H2O为原料,聚乙二醇(PEG-1000)作为分散剂,利用沉淀法制备出SnO2纳米粉体,采用扫描电镜(SEM)和X-射线衍射(XRD)对其形貌和微观结构进行表征.并以其作为基底材料以离子的形式掺杂摩尔比为1%的Ni2+作为气敏材料,制作掺杂和未掺杂两种旁热式气敏元件,测试其对乙醇、甲醇和丙酮的气敏特性.发现在较低的工作温度下两种元件对三种气体都有较高的敏感性,同时Ni离子的掺杂对三种气体的灵敏度有不同的影响,对乙醇表现出很好的选择性.     

Fe/Ni-MOF衍生的Fe3+掺杂NiO丙酮传感器研究

采用水热法制备了球形纳米花状Fe/Ni-MOF,通过煅烧制备其衍生物Fe³⁺掺杂的NiO(标记为Fe-NiO),对系列Fe-NiO进行表征并制备成传感器研究其气敏性能。通过表征和测试发现, Fe³⁺是通过原位合成进入NiO晶格中取代Ni²⁺, Fe³⁺的加入不仅有助于Fe-NiO在高温煅烧后保持更好的形貌,而且能够降低NiO中的载流子浓度增加空气中的电阻,有助于传感器性能的提升。Fe³⁺掺杂量为15%的样品对5×10^-6丙酮具备最佳的传感性能,灵敏度达到327.4%,气敏性能较纯NiO提升了13倍,在150℃的工作温度下具有快的响应速度(7 s),电阻恢复90%需26 s,可在短时间内用于检测丙酮目标气体。Fe-NiO-15%制成的丙酮传感器具有良好的重复性、稳定性,受湿度影响小。     

一种基于 MXene 的Fe2O3/Nb2O5/Nb4C3Tx 高灵敏丙酮传感器

MXene 具有较大比表面积和优异的导电性, 当与金属氧化物半导体结合时可以抑制片层团聚, 还可以大大提高载流子转移速率, 提高气敏性能。通过简单的水热和煅烧两步法成功合成了Fe₂O₃/Nb₂O₅/Nb₄C₃T_x 三元复合材料。通过表征, Fe₂O₃ 微米球分布在 MXene 纳米片层之间。气敏测试结果表明, 与原始Fe₂O₃相 比, Fe₂O₃/Nb₂O₅/Nb₄C₃T_x 传感器对丙酮的响应能力有明显的提高。传感器灵敏度高, 选择性较好, 对环境中 浓度为 5 ×10^?6 的丙酮响应高 (R_a /R_g = 7.81, 30% RH), 响应和恢复速度快, 具有出色的重复性和长期稳定性。Fe₂O₃/Nb₂O₅/Nb₄C₃T_x 传感器具有良好的气敏性能, 主要因为三元复合材料提供了较大比表面积和丰富的氧空位, 增强了活性位点, 使得气体易于在传感器表面扩散, 为开发丙酮敏感复合材料提供了参考。     

Solvothermal preparation and characteristics of Sn-doped In2O3

Sn-doped In2O3 （ITO） nanopowders were prepared in ethanol solvent by solvothermal process. The effects of the solvothermal temperature, coprecipitation pH value and SnO2 content on the products phase and microwave absorption were investigated by X-ray diffractometry and microwave reflectance. ITO nanopowders with cubic structure can be respectively prepared at 250 and 270 ℃ for 6 h. The prepared product is InOOH or the mixture of InOOH and In3Sn4O12 when the solvothermal temperature is below 250℃. With rising solvothermal temperature and prolonging time, the absorption of the ITO powders gradually decreases. The products are ITO nanopowders by coprecipitating at pH=9 or 11, but ITO powders with Sn3O4 at pH=6. The absorption of powders prepared at pH=6 is better than that at any other pH value. The products are all ITO nanopowders and crystal size reduces with increasing SnO2 content. The microwave absorption of ITO nanopowders with SnO2 content of 8% （mass fraction） is the best among samples with different SnO2 contents.     

核壳结构Au@SnO2的制备及其低温下的正丁醇气敏性能

以SnCl₄·5H₂O和HAuCl₄·3H₂O为原料,以L-半胱氨酸为连接剂,通过水热法制备Au@SnO₂核壳结构纳米颗粒。由透射电子显微镜和X射线衍射结果发现二氧化锡（SnO₂）与金（Au）颗粒的平均粒径分别为4.9 nm和10.5 nm。SnO₂颗粒堆积在Au核表面形成了具有多孔壳结构的复合材料,比表面积达到178.82 m²/g,总孔隙体积为0.165 1 cm³/g。Au@SnO₂核壳结构的存在使得传感器对正丁醇具有优异的气敏性能,在80 ℃时的灵敏度达到8 669.15,检测极限达到3.9×10^-3 g/m³,显著提高了SnO₂的灵敏度,并降低了最佳工作温度。     

Degradation of p-nitrotoluene by O3/H2O2 process and oxidation mechanism

The degradation of p-nitrotoluene by O3/H2O2 process in a bubble contact column was investigated. Effects of the molar ratio of hydrogen peroxide to ozone,pH value and t-butanol on the oxidation process were discussed. It was found that the proper H2O2/O3 molar ratio for the degradation of p-nitrotoluene was around 0.6, different pH values and the presence of t-butanol highly influenced the removal efficiency of p-nitrotoluene. 5-methyl-2-nitrophenol, 2-methyl-5-nitrophenol, (4-nitrophenyl) methanol, 5-(hydroxymethyl)-2-nitro phenol, acetic acid, 2-methylpropane diacid and 2-(hydroxylmethyl)propane diacid were identified as degradation intermediates and products through GC-MS. Radical reaction mechanism and degradation pathway were proposed based on the results of experiments. It is deduced that the benzene ring of p-nitrotoluene can be only destroyed by hydroxyl radicals through a polyhydroxy intermediate pathway. Then unstable polyhydroxy intermediates can be oxidized to different acids with low molecular weight rapidly.     

Synthesis of Ag@Al2O3 Core-shell Structure Nanoparticles and Their Enhancement Effect on Dielectric Properties for Ag@Al2O3/Polyimide Nanocomposites

A novel core-shell structure Ag@Al2O3 nano-particles were synthesized and doped into polyimide as conductive fillers to prepare the composite films with high dielectric properties and low dielectric loss. The morphology and structures of the Ag@Al2O3 nano-particles were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), and UV-visible spectroscopy. All the results proved that the Ag@Al2O3 nano-particles had a typical core-shell structure, for the Ag particles were coated by Al2O3 shell and the average sizes of Ag@Al2O3 particles were between 30 to 150 nm. The as-prepared Ag@Al2O3 nanoparticles were doped into the polyimide with different mass fractions to fabricate the Ag@Al2O3/PI composite films via in-situ polymerization process. SEM analysis of composite films showed that the Ag@Al2O3 nanoparticles homogeneously dispersed in polyimide matrix with nanoscale. As dielectric materials for electronic packaging systems, the Ag@Al2O3/PI composites exhibited appropriate mechanical properties and enhanced dielectric properties, including greatly enhanced dielectric constant and just a slight increase in dielectric loss. These improvements were attributed to the core-shell structure of fillers and their fine dispersion in the PI matrix.     

Pressureless reactive sintering mechanism of nanocrystalline Bi2O3-Y2O3 solid electrolyte

The nanocrystalline Bi2O3-Y2O3 solid electrolyte material was synthesized by pressureless reactive sintering process with Bi2O3 and Y2O3 nano mixed powder as raw materials, which was prepared by a chemical coprecipitation process. The study on the behavior of nano δ-Bi2O3 formation and its grain growth showed that the solid solution reaction of Y2O3 and β-Bi2O3 to form δ-Bi2O3occurs mainly in the initial stage of sintering process, and nano δ-Bi2O3 crystal grains grow approximately following the rule of paracurve ((D-D0)2=K.t) during sintering process. After sintered at 600℃ for 2 h, the samples could reach above 96% in relative density and have dense microstructure with few remaining pores, the δ-Bi2O3 grains are less than 100 nm in size.