反胶束软模板法合成PANI/TiO2纳米棒复合材料及其性能研究

以阳离子表面活性剂十六烷基三甲基溴化胺(CTAB)形成的反胶束为模板,制备了一系列不同纳米TiO2含量的PANI/TiI2纳米复合材料.利用FTIR,UV-Vis,TG,TEM和荧光光谱等方法对产物进行了结构表征和性能研究.探讨了反胶束体系中PANI/TiO2复合纳米棒形成的自组装机理.结果表明:复合材料主要为直径30～40 nm,长约400 nm的PANI/TiO2复合纳米棒,二氧化钛纳米粒子与聚苯胺大分子之间存在强的相互作用,并对复合材料的热稳定性起到提高作用,PANI/TiO2纳米复合材料在紫外和可见光区域均有吸收,并在416 nm处激发产生荧光,荧光强度随着掺杂TiO2含量的提高得到了较大的增强.通过PANI/TiO2纳米棒复合材料中的激子离化和电荷传输过程探讨了PANI/TiO2的荧光量子效率和荧光强度增加的机理.     

CdSe纳米粒子负载的TiO2纳米带复合材料制备及其可见光催化性能

采用水热法制备了CdSe 纳米粒子负载的锐钛矿型TiO2纳米带复合材料,并对产物的晶体结构、形貌尺寸、CdSe负载量及其可见光催化性能进行了测试.结果表明,产物中CdSe纳米粒子以闪锌矿型面心立方结构负载在TiO2纳米带表面,负载量可控;虽然CdSe纳米粒子的负载降低了TiO2纳米带比表面积,但是显著增强了产物可见光吸...     

Ag/TiO2纳米材料的制备和光致变色性能研究

 采用光催化还原法在不同温度热处理的TiO2薄膜表面沉积Ag纳米颗粒,制备了Ag/TiO2纳米薄膜材料。通过UV-Vis吸收光谱表征对比了不同温度热处理的TiO2对Ag粒子光催化沉积的影响,发现500℃退火处理TiO2薄膜较利于Ag纳米粒子的光催化沉积;在650 nm红色激光照射下,500℃退火处理的Ag/TiO2样品具有明显的光致变色现象,对此变色过程中涉及的机理进行了讨论,且发现随着Ag纳米颗粒光催化沉积时间的增长,Ag/TiO2薄膜光致变色的响应速率提高,但Ag纳米颗粒过多会抑制Ag/TiO2薄膜的变色响应速率。     

纳米颗粒TiO2/HFC134a工质导热系数实验研究

本文采用瞬态热线法对纳米颗粒TiO2/HFC134a工质的导热系数进行了实验研究.结果表明,相对于HFC134a,纳米颗粒TiO2/HFC134a工质的导热系数增大,提高比例随着颗粒浓度和温度的提高而增大.     

纳米颗粒TiO2/HFC134a工质对流换热实验研究

本文建立了纳米颗粒/制冷剂工质换热性能实验台,对实验系统进行了检验,并首次进行了纳米颗粒TiO2/HFC134a工质水平管内的单相对流换热实验研究,纳米颗粒的浓度为0.01、0.025和0.05 g/L,并与纯质HFC134a的结果相比较.结果发现:TiO2/HFC134a工质的单相对流换热系数降低,且随着纳米颗粒浓度的增大,降低程度增大.分析原因纳米颗粒在换热表面的沉积是造成这一结果的关键因素.     

聚(2-甲氧基-5-辛氧基)对苯乙炔/TiO2纳米复合材料的光物理性能研究

通过原位强碱诱导下的脱氯化氢缩合聚合法制备了一系列不同纳米TiO2含量的聚(2-甲氧基-5-辛氧基)对苯乙炔/纳米二氧化钛(PMOCOPV/TiO2)光电复合材料。红外光谱和拉曼光谱证实了在纳米TiO2表面的包覆层为PMOCOPV。紫外-可见吸收光谱表明随着TiO2含量的增加PMOCOPV/TiO2纳米复合材料的吸收强度提高。高分辨透射电镜观察发现PMOCOPV/TiO2是具有核-壳结构的纳米复合粒子,直径约30 nm,其中PMOCOPV包覆层的厚度约为8~10 nm。荧光光谱研究表明,PMOCOPV/TiO2纳米复合材料的最大发射波长随着TiO2含量的增加发生红移,荧光寿命约为1 ns,且随着TiO2含量的增加荧光强度和荧光寿命得到显著提高,并通过PMOCOPV/TiO2纳米复合材料中的激子离化和电荷传输过程以及复合材料中的电势能级探讨了PMOCOPV/TiO2的荧光量子效率和荧光强度增加的机理。     

光致电子转移对Alizarin敏化TiO_2纳米粒子Raman光谱特性的影响

结合理论和实验研究了茜素Alizarin(Alz)染料敏化TiO2纳米粒子体系的光致电子转移对Alz Raman光谱特性的影响.结果表明:Alz染料敏化TiO2纳米粒子吸收光谱的红移和荧光光谱的淬灭归因于从被吸附的Alz染料分子激发态和电荷转移复合物(Alz/TiO2)到TiO2纳米粒子导带的光致电子转移;超快光致界面电子的转移有效地增强了被吸附在界面处Alz染料分子的C=C键伸展振动、C=O羧基伸展振动和C-O键伸展振动.     

Ag-TiO_2/KIT-6复合纳米光催化剂的研究

以有序介孔SiO2(简称KIT-6)为载体,采用钛酸丁酯水解法将纳米TiO2与KIT-6复合,并通过沉积沉淀法将纳米Ag粒子负载于其上,首次制得Ag-TiO2/KIT-6复合光催化剂,并采用相同的方法制备了一系列相关的催化剂.以光催化降解甲基橙来评价其催化性能,光催化活性顺序为Ag-TiO2/KIT-6＞Ag/TiO2＞TiO2/KIT-6＞TiO2＞Ag/KIT-6.利用XRD、N2物理吸附、XPS、UV-Vis DRS和TEM对系列催化剂进行表征,结果表明Ag-TiO2之间形成的异质结和催化剂的大比表面积是Ag-TiO2/KIT-6具有最高光催化活性的重要原因.其中Ag-TiO2之间的异质结结构,有效抑制了光生电子和光生空穴在TiO2表面和体相内部的复合,提高了光催化活性;此外Ag-TiO2/KIT-6的大比表面积大大提高了催化剂的吸附能力,增加了催化剂与污染物的接触,达到快速光催化降解污染物的目的.     

TiO2/5A光催化降解水中CN-的催化活性

采用溶胶-凝胶-浸渍法制备TiO2/5A型催化剂,以其对水样中CN-降解率的大小来评价催化剂的光催化活性,并与P25型纳米TiO2催化效果作比较,从而探讨5A型分子筛负载纳米TiO2的百分含量、催化剂加入量、水样的pH值及CN-初始浓度对TiO2/5A光催化降解水中CN-催化活性的影响.结果表明:5A型分子筛负载纳米TiO2的量为20％、加入量为1.5g/L、pH=10、CN-初始浓度为50mg/L,反应时间为3h时,降解率达88.64％,且优于P25型纳米TiO2的降解效果.     

二氧化钛纳米流体的固液相变特性

采用“两步法”制备出不同浓度的TiO2-H2O纳米流体,选用紫外分光光度法对纳米流体的分散稳定性进行了评价,使用差示扫描量热仪对纳米流体以及基液一去离子水的固液相变过程进行了测试。实验结果表明：纳米流体的分散稳定性随着TiO2粒子质量浓度的增大先增强后减弱;添加纳米颗粒可以促进去离子水的异质成核,减小其固液相变过冷度;...     

Electron transport properties of TiO_2 shell on Al_2O_3 core in dye-sensitized solar cells

The performance of dye-sensitized solar cells(DSSCs)is strongly affected by the properties of semiconductor nanoparticles.In this work,we used TiO_2 particles prepared by TiCl_4 hydrolysis n times on Al_2O_3 films(A/T(n)),and investigated morphology,photoelectric,and electron transport properties of A/T(n).The TiO_2 shell was composed of 10-20 nm nanoparticles and the number of nanoparticles increased with increasing TiCl_4 treatment times.The highest photoelectric conversion efficiency of 3.23% was obtained as A/T(4).IMPS results indicated that electron transport rate was high enough to conduct current,and was not the dominating effect to limit the Jsc.Jsc was mainly determined by dye loading on TiO_2 and the interconnection of TiO_2.These may provide a new strategy for preparing semiconductor working electrodes for DSSC.     

TiO_2 composite electron transport layers for planar perovskite solar cells by mixed spray pyrolysis with precursor solution incorporating TiO_2 nanoparticles

Perovskite solar cells with planar structure are attractive for their simplified device structure and reduced hysteresis effect. Compared to conventional mesoporous devices, TiO_2 porous scaffold layers are removed in planar devices. Then,compact TiO_2 electron transport layers take the functions of extracting electrons, transporting electrons, and blocking holes.Therefore, the properties of these compact TiO_2 layers are important for the performance of solar cells. In this work, we develop a mixed spray pyrolysis method for producing compact TiO_2 layers by incorporating TiO_2 nanoparticles with different size into the precursor solutions. For the optimized nanoparticle size of 60 nm, a power conversion efficiency of 16.7% is achieved, which is obviously higher than that of devices without incorporated nanoparticles(9.9%). Further investigation reveals that the incorporation of nanoparticles can remarkably improve the charge extraction and recombination processes.     

Synchrotron small angle x-ray scattering study of dye-sensitized／-unsensitized TiO2 nanoparticle colloidal solution

The wide-gap semiconductor TiO_2 nanoparticles with and without dye sensitization have been studied by small angle x-ray scattering using synchrotron radiation. Surface properties of the colloidal TiO_2 nanoparticles have been analysed in terms of the surface fractal dimensions (D_s), showing that D_s changes from 3.25 to 2.34 when TiO_2 nanoparticles are sensitized by ATRA (all-trans-retinoic acid), which reveals that the surface of the particles become relatively smooth after dye sensitization. The size distribution of gyration radius of TiO_2 nanoparticles in the colloids M(R_g) has been successfully determined by the Shull－Roess method. The main peak of M(R_g) for the unsensitized TiO_2 colloid is located at 2.1nm, corresponding to a spherical diameter of 5.4nm, and this value for the ATRA sensitized TiO_2 increases to 2.4nm, indicating a spherical diameter of 6.4nm. Such a size enlargement of TiO_2 nanoparticles suggests that there is a coating of ATRA on the TiO_2 surface, supporting the view that a monolayer of the dye has been attached to the surface of the TiO_2 nanoparticle.     

FTIR-ATR技术考察TiO2膜对油酸的光催化氧化性能

采用Sol-Gel和PVD法在玻璃、陶瓷、铝片表面制备出TiO2膜,直接将食用油中的主成分油酸用溶剂稀释后均匀涂在膜表面,采用FTIR-ATR技术实现了对膜样品光催化自清洁性能的快速准确评价,并通过测量水的接触角评价了膜的亲水性。结果表明,Sol-Gel法和PVD法制备的TiO2/玻璃膜都具有较好的光致亲水性和光催化降解油酸性能,两者的亲水性没有明显差别,但前者的光催化活性稍优于后者。比较Sol-Gel法制备的TiO2/玻璃、TiO2/陶瓷和TiO2/铝片膜对油酸的光催化降解性能发现,光照3·5h后3个样品的降解率分别为92%,85%和46%,表明基底材料性质对TiO2膜的光催化活性有明显影响,镀在非导电性玻璃和陶瓷表面的TiO2膜比镀在导电性金属铝表面的TiO2膜对油酸有更高的光催化降解能力。     

Carbon-nanodot-coverage-dependent photocatalytic performance of carbon nanodot/TiO_2 nanocomposites under visible light

Carbon nanodots(CDs) with visible absorption band and TiO_2 are integrated to enhance the photosensitivity of TiO_2.The CD/TiO_2 nanocomposites show obvious CD-coverage-dependent photocatalytic performance. The CD/TiO_2 nanocomposites with moderate CD coverge exhibit the highest photocatalytic activity after being irradiated with visible light, which is more excellent than that of TiO_2. Too little CD coverage could result in poor visible light absorption, which limits the photocatalytic performance of CD/TiO_2 nanocomposites. While, too much CD coverage weakens the photocatalytic activity of CD/TiO_2 nanocomposites by restraining the extraction of conduction band electrons within TiO_2 to generate active oxygen radicals and the electron transfer(ET) process from CDs to TiO_2. These results indicate that rational regulation of CD coverage and the realization of efficient ET process are important means to optimize the photocatalytic performance of CD/TiO_2 nanocomposites.     

Growth and Physical Properties of CdS/TiO_2 Bilayer by Plasma-Based Method

The titanium oxide(TiO_2) nanotubes have attracted attention for their use in dye-sensitized solar cells as photoanode. In this study semiconducting cadmium sulfide(CdS) nanoparticles are grown on top opened TiO_2 nanotubes arrays by radio-frequency magnetron sputtering. X-ray diffraction, scanning electron microscopy,transmission electron microscopy and diffuse reflection spectra are used to study structural, morphological and optical properties of the CdS/TiO_2 bilayer.     

超疏水纳米结构表面池沸腾特性

本文通过采用物理气相沉积法于TiO2纳米管阵列表面修饰一层聚四氟乙烯(PTFE)纳米颗粒,得到超疏水表面,并研究此超疏水纳米结构表面的池沸腾特性.研究表明,超疏水纳米结构表面沸腾特性类似于膜沸腾,沸腾工质难以浸润该表面,其沸腾传热系数及临界热流密度均较低.分析表明,固液处于Cassie-Baxter接触状态,纳米结构表...     

Enhanced ultraviolet emission from ZnO thin film covered by TiO_2 nanoparticles

A ZnO thin film covered by TiO2 nanoparticles is prepared by electron beam evaporation. The structure and surface morphology of the sample are analyzed by X-ray diffraction （XRD） and atomic force microscopy （AFM）, respectively. Photoluminescence is used to investigate the fluorescent property of the ample. The results show that the ultraviolet （UV） emission of the ZnO thin film is greatly enhanced after it is covered by TiO2 nanoparticles while the green emission is suppressed. The enhanced UV emission mainly results from the fluorescence resonance energy transfer （FRET） between ZnO thin film and TiO： nanoparticles. This TiO2-ZnO composite thin film can be used to fabricate high-efficiency UV emitters.