用SAXS和XRD方法研究Ti02纳米颗粒微观结构

用溶胶一凝胶方法制备了TiO2纳米样品.并对该样品在300℃到800℃温度区域进行了退火处理.应用同步辐射x射线粉未衍射(XRD)方法研究了经不同热处理温度的TiO2纳米颗粒的结构相变.应用同步辐射小角x射线散射(SAXS)方法研究了TiO2纳米颗粒的表面分形与界面特性.得到纳米颗粒粒度与退火温度的变化规律,讨论r表面界面特征与相变的关系.     

宽带隙半导体TiO2纳米溶胶原位变温的X射线小角散射研究

对宽带隙半导体TiO₂纳米粒子水溶液,开展了原位变温SAXS研究.采用Shull-Roess方法,我们确定了TiO₂纳米粒子在水溶液中的回转半径的尺寸分布,M(R_g).结果表明,在常温25°C下,M(R_g)的极大峰位于2.3nm,对应于2.9nm的球形粒子直径,在80°C时增加到3.2nm,对应于8.2nm的球形粒子直径.这些结果有利于理解染料敏化TiO₂纳米太阳能电池的光-电子特性及其转换效率随温度的变化规律.     

金属离子掺杂对TiO2/白云母纳米复合材料中TiO2的颗粒形态及相组成的影响

采用化学液相沉积法制备了系列未掺杂和掺杂不同金属离子的TiO2白云母纳米复合材料.利用扫描电子显微镜(SEM),x射线衍射(XRD)对其TiO2薄膜的TiO2颗粒形态和相组成进行了详细研究.结果表明,TiO2颗粒在15—50nm之间;除球形颗粒外,掺杂Mn2+,Zn2+的样品中还出现有金红石柱状颗粒.TiO2薄膜中相组成以锐钛矿、金红石共存为特征;掺杂金属离子对TiO2相组成的影响取决于金属离子的离子半径、电荷及配位体特征. 关键词： 金属离子掺杂 TiO2 颗粒形态 相组成     

中空TiO2纳米球的制备

报道了一种新的无机模板法合成中空的TiO₂纳米球,该法以TiCl₄为钛源,中空Sb₂S₃微球为模板,利用TiCl₄水解产生的TiO₂沉积在模板的表面,同时产生的HCl消蚀Sb₂S₃,一步制备中空纳米材料。     

利用小角X射线散射技术研究组分对聚酰亚胺/Al2O3杂化薄膜界面特性与分形特征的影响

采用溶胶-凝胶方法制备无机纳米杂化聚酰亚胺(PI),应用同步辐射小角X射线散射(SAXS)方法研究不同组分杂化PI薄膜的界面特性与分形特征.研究结果表明:散射曲线不遵守Porod定理,形成负偏离,说明薄膜中有机相与Al₂O₃纳米颗粒间存在界面层,界面层厚度在0.54 nm到1.48 nm范围内;随无机纳米组分增加,界面层厚度增加,有机相与无机相作用变强;无机纳米颗粒同时具有质量分形和表面分形特征,其分布、集结是一种非线性动力学过程;随组分增加,其质量分形维数降低 关键词： 小角X射线散射 纳米杂化 聚酰亚胺 界面     

Pt/C催化剂中纳米Pt颗粒团聚效应的小角X射线散射

 应用小角X射线散射(SAXS)技术,对乙二醇合成法、浸渍还原法和微波加热法制备的Pt/C催化剂粉体内纳米Pt颗粒的团聚效应进行了研究,得到了不同方法制备的Pt颗粒及其团聚体的特征尺寸、体积分布、表面积变化、团聚程度等信息,并利用透射电镜（TEM）对3种样品进行了测试。实验结果表明:微波加热法制备的催化剂中,Pt颗粒较好地分散于C载体上,且Pt颗粒具有尺度小、分布范围窄、总表面积大和团聚体较少等特征;常规浸渍和乙二醇还原两种方法制备的催化剂中Pt颗粒大小分布相似,但乙二醇还原法制备的催化剂总表面积和团聚体尺度更大,数量也更多。     

Pt/C催化剂中纳米Pt颗粒团聚效应的小角X射线散射

应用小角X射线散射(SAXS)技术,对乙二醇合成法、浸渍还原法和微波加热法制备的Pt/C催化剂粉体内纳米Pt颗粒的团聚效应进行了研究,得到了不同方法制备的Pt颗粒及其团聚体的特征尺寸、体积分布、表面积变化、团聚程度等信息,并利用透射电镜（TEM）对3种样品进行了测试。实验结果表明:微波加热法制备的催化剂中,Pt颗粒较好地分散于C载体上,且Pt颗粒具有尺度小、分布范围窄、总表面积大和团聚体较少等特征;常规浸渍和乙二醇还原两种方法制备的催化剂中Pt颗粒大小分布相似,但乙二醇还原法制备的催化剂总表面积和团聚体尺度更大,数量也更多。     

不同尺寸锐钛矿结构TiO2纳米晶的高压相变研究

本文利用溶胶-凝胶法合成出5.6 nm、8.6 nm和19.4 nm三种尺寸的锐钛矿结构TiO2纳米晶, 并利用金刚石对顶砧压机结合Raman光谱技术研究了尺寸效应对其在23 GPa高压下结构相变的影响。结果发现, 对于5.6 nm和8.6 nm的样品, 加压到23.2 GPa和22.5 GPa的压力时没有发生结构相变, 而是转变为无定型结构, 卸除压力后, 依然保持为无定型; 而19.4 nm的样品在约11.3 GPa时逐渐转变为单斜斜锆石结构, 在卸压后转变为α-PbO2结构。相对于块材, 尺寸越小, 相变压力越大。基于吉布斯自由能理论, 尺寸减小引起的表面能增大被认为是相变压力变大的主要原因。     

纳米晶锐钛矿相TiO2的非简谐效应和声子局域

对晶粒尺寸为194,86和56nm的纳米晶锐钛矿相TiO₂,进行了从83到723K的变温拉曼散射测量,并对E_g(1)模式进行了详细研究.根据非简谐效应和声子局域模型,对E_g(1)拉曼峰进行了拟合与计算.结果表明,以上三种纳米晶粒的晶格振动机理,在本质上是相同的.三声子过程对频率蓝移起主要作用.为了得到很好的拟合,需要同时考虑三声子和四声子过程.随着温度的升高,四声子过程增强,并对三声子过程起抵消作用.与非简谐衰减相关的声子寿命随着晶粒 关键词： 2')" href="#">纳米晶TiO₂ 拉曼散射 非简谐耦合 声子局域     

纳米TiO2多孔薄膜电极平带电势的研究

采用光谱电化学方法研究了纳米TiO₂多孔薄膜电极的平带电势,获得了薄膜厚度以及TiCl₄处理对纳米TiO₂薄膜电极平带电势的影响情况,并研究了平带电势对染料敏化太阳电池光伏性能的影响.结果表明,可以通过检测纳米TiO₂电极平带电势的变化趋势来反映电池中TiO₂电极平带电势的变化趋势.随着TiO₂电极膜厚的增加,其平带电势将向正方向移动,导致对应电池的开路电压随之减小.另外,经 关键词： 平带电势 2')" href="#">纳米TiO₂ 染料敏化 太阳电池     

Light-induced antifungal activity of TiO2 nanoparticles/ZnO nanowires

Antifungal activity of TiO₂/ZnO nanostructures under visible light irradiation was investigated. A simple chemical method was used to synthesize ZnO nanowires. Zinc acetate dihydrate, Polyvinyl Pyrrolidone and deionized water were used as precursor, capping and solvent, respectively. TiO₂ nanoparticles were deposited on ZnO nanowires using an atmospheric pressure chemical vapor deposition system. X-ray diffraction pattern of TiO₂/ZnO nano-composite has represented the diffraction peaks relating to the crystal planes of the TiO₂ (anatase and rutile) and ZnO. TiO₂/ZnO nanostructure antifungal effect on Candida albicans biofilms was studied and compared with the activity of TiO₂ nanoparticles and ZnO nanowires. The high efficiency photocatalytic activity of TiO₂ nanoparticles leads to increased antifungal activity of ZnO nanowires. Scanning electron microscope was utilized to study the morphology of the as prepared nanostructures and the degradation of the yeast.     

Uniform thin films of TiO2 nanoparticles deposited by matrix-assisted pulsed laser evaporation

We report morphological and optical properties of a colloidal TiO₂ nanoparticle film, deposited on a quartz substrate by using the Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique. Atomic Force Microscopy demonstrated that a good uniformity of the deposition can be obtained. The presence of agglomerates with dimensions of about 1 μm in size was noticed. Form UV-vis transmission spectra, recorded in the 200-800 nm range, the optical constants and the energy gap were determined besides the film thickness. The optical constants resulted in agreement with the values reported in literature for TiO₂ nanoparticle thin films.     

Surface-modified antibacterial TiO2/Ag nanoparticles: Preparation and properties

Studies were performed on surface modification of antibacterial TiO₂/Ag⁺ nanoparticles by grafting γ-aminopropyltriethoxysilane (APS). The interfacial structure of the modified particles was characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric analysis. The thickness of the surface layer was determined by using Auger electron spectroscopy (AES). The results show that APS is chemically bonded to the surface of antibacterial TiO₂/Ag⁺ nanoparticles. Furthermore, the modified particles were mixed in PVC to prepare composites whose antibacterial property was investigated. The results suggest that surface modification has no negative effect on antibacterial activity of TiO₂/Ag⁺ nanoparticles and PVC-TiO₂/Ag⁺ composites exhibits good antibacterial property.     

The dispersion study of TiO2 nanoparticles surface modified through plasma polymerization

In this study, the surface of TiO₂ nanoparticles was modified through plasma polymerization, which is a dry coating method at room temperature. The surface morphology of TiO₂ nanoparticles was characterized by high-resolution transmission electron microscope (HRTEM). The dispersion behavior of TiO₂ nanoparticles in water and ethyl glycol was investigated by laser size distribution and ultraviolet–visible absorption spectrum. TiO₂ nanoparticles were coated with a thin film through plasma polymerization, which prevents the agglomeration and improves the dispersion behavior of TiO₂ nanoparticles.     

XPS and XRD investigation of Co/Pd/TiO2 catalysts by different preparation methods

In the article, the Co/Pd/TiO₂, Co/TiO₂ and Pd/TiO₂ catalysts prepared by the impregnation and sol–gel method are studied by using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The result shows that Co²⁺ and metal Pd may act as the active center for the direct synthesis of acetic acid from CH₄ and CO₂ by a two-step reaction sequence. When the catalysts are prepared by the sol–gel, Co²⁺ can enter the crystal lattice of the TiO₂, causing the phase transition from anatase to rutile at lower temperature, but existence of Pd²⁺ can prevent from the phase transition. When the catalysts are prepared by the impregnation, the phase transition is inhibited not only Co²⁺ but also Pd²⁺.     

Photoinduced interaction of colloidal TiO2 nanoparticles with lysozyme: Evidences from spectroscopic studies

The interaction between colloidal TiO₂ nanoparticles and lysozyme (LYSO) was studied using absorption, steady state and time resolved fluorescence, FT-IR and synchronous fluorescence spectroscopic measurements. The apparent association constant has been deduced from the absorption spectral changes of LYSO-colloidal TiO₂ nanoparticles using Benesi-Hildebrand equation. The number of binding sites and the apparent binding constant were calculated from relevant fluorescence data. Based on Forster's non-radiation energy transfer theory, distance between the donor (LYSO) and the acceptor (TiO₂) has also been calculated. The conformational changes of LYSO have been analyzed by means of FT-IR and synchronous fluorescence spectroscopy. In addition, the effect of metal ions on the binding constants of LYSO-TiO₂ complex has also been discussed.     

Synthesis of anatase TiO2 nanowires by modifying TiO2 nanoparticles using the microwave heating method

Anatase TiO₂ nanowires with a diameter of 5-10 nm and length of 500 nm to 2 μm have been successfully synthesized by modifying TiO₂ nanoparticles (P25) using the microwave heating method. The microwave power, reaction pressure, and reaction time for the synthesis of TiO₂ nanowires were 500 W, 0.5-3.0 MPa (corresponding to a temperature range of 175-260), and 40-70 min, respectively. X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and the BET techniques were used to investigate the phase structures, morphologies, and specific surface areas of the TiO₂ nanowires. The effects of reaction time, pressure, and different post-treatment processes on the microstructures of TiO₂ nanowires were discussed. It has been shown that the microwave heating method is efficient in transforming TiO₂ nanoparticles to anatase TiO₂ nanowires.     

Effect of annealing on TiO2 nanoparticles

TiO₂ nanoparticles have been prepared by simple chemical precipitation method and annealed at different temperatures. The as-prepared TiO₂ are amorphous, and they transform into anatase phase on annealing at 450 °C, and rutile phase on annealing at 900 °C. The X-ray diffraction results showed that TiO₂ nanoparticles with grain size in the range of 21–24 nm for anatase phase and 69–74 nm for rutile phase have been obtained. FESEM images show the formation of TiO₂ nanoparticles with small size in structure. The FTIR and Raman spectra exhibited peaks corresponding to the anatase and rutile structure phases of TiO₂. Optical absorption studies reveal that the absorption edge shifts towards longer wavelength (red shift) with increase of annealing temperature.     

Ultrafine anatase TiO2 nanoparticles produced in premixed ethylene stagnation flame at 1 atm

Nano-sized titanium oxide particles were synthesized in a stationary, laminar, premixed, stagnation flame burning an ethylene–oxygen–argon mixture at an equivalence ratio of 0.36 under the atmospheric pressure. The titanium precursor, titanium tetraisopropoxide (TTIP), was fed into the flame by a carrier argon flow through a heated TTIP bath. Particles synthesized in this flame were characterized for their size distribution, morphology, phase purity, and crystal structure, by scanning mobility particle sizer, transmission electron microscopy, and X-ray diffraction. It was found that the mean diameter of the particles was highly controllable and ranged from 3 to 6 nm depending on TTIP loading. The particle size was nearly uniform, and particles appeared to be single crystals without excessive aggregation. XRD analyses show that particles directly synthesized in the flame are pure anatase. Upon sintering and size growth on the flame stabilizer, a notable portion of particles transformed into rutile with much larger crystal sizes.     

Synthesis of TiO2 rutile nanoparticles by PLA in solution

This paper describes the synthesis of TiO₂ nanoparticles by laser ablation in solution synthesis (Lasis). The laser excimer beam passes through a focusing lens and it is sent to the reaction chamber. The frequency used during the synthesis was 20 Hz, intensity 26 kV The metal ablated by the laser beam undergoes an oxidation process resulting from the reaction with water. We obtain TiO₂ nanoparticles with average size of 6.5 nm, crystallized in the rutile structure. The crystallographic and morphological structure was studied by transmission electron microscopy.