Ferromagnetism and Ru-Ru distance in SrRuO3 thin film grown on SrTiO3 (111) substrate

TiO₂ hierarchical nanostructures with secondary growth have been successfully synthesized on electrospun nanofibers via surfactant-free hydrothermal route. The effect of hydrothermal reaction time on the secondary nanostructures has been studied. The synthesized nanostructures comprise electrospun nanofibers which are polycrystalline with anatase phase and have single crystalline, rutile TiO₂ nanorod-like structures growing on them. These secondary nanostructures have a preferential growth direction [110]. UV–vis spectroscopy measurements point to better dye loading capability and incident photon to current conversion efficiency spectra show enhanced light harvesting of the synthesized hierarchical structures. Concomitantly, the dye molecules act as spacers between the conduction band electrons of TiO₂ and holes in the hole transporting medium, i.e., spiro-OMeTAD and thus enhance open circuit voltage. The charge transport and recombination effects are characterized by electrochemical impedance spectroscopy measurements. As a result of improved light harvesting, dye loading, and reduced recombination losses, the hierarchical nanofibers yield 2.14% electrochemical conversion efficiency which is 50% higher than the efficiency obtained by plain nanofibers.     

Improvement in the photoelectrochemical responses of PCBM/TiO2 electrode by electron irradiation

ABSTRACT: The photoelectrochemical (PEC) responses of electron-irradiated 66-phenyl-C61-butyric acid methyl ester (PCBM)/TiO2 electrodes were evaluated in a PEC cell. By coating PCBM on TiO2 nanoparticle film, the light absorption of PCBM/TiO2 electrode has expanded to the visible light region and improved the PEC responses compared to bare TiO2 electrode. The PEC responses were further improved by irradiating an electron beam on PCBM/TiO2 electrodes. Compared to non-irradiated PCBM/TiO2 electrodes, electron irradiation increased the photocurrent density and the open-circuit potential of PEC cells by approximately 90% and approximately 36%, respectively at an optimum electron irradiation condition. The PEC responses are carefully evaluated correlating with the optical and electronic properties of electron-irradiated PCBM/TiO2 electrodes.     

A maskless synthesis of TiO2-nanofiber-based hierarchical structures for solid-state dye-sensitized solar cells with improved performance

TiO₂ hierarchical nanostructures with secondary growth have been successfully synthesized on electrospun nanofibers via surfactant-free hydrothermal route. The effect of hydrothermal reaction time on the secondary nanostructures has been studied. The synthesized nanostructures comprise electrospun nanofibers which are polycrystalline with anatase phase and have single crystalline, rutile TiO₂ nanorod-like structures growing on them. These secondary nanostructures have a preferential growth direction [110]. UV–vis spectroscopy measurements point to better dye loading capability and incident photon to current conversion efficiency spectra show enhanced light harvesting of the synthesized hierarchical structures. Concomitantly, the dye molecules act as spacers between the conduction band electrons of TiO₂ and holes in the hole transporting medium, i.e., spiro-OMeTAD and thus enhance open circuit voltage. The charge transport and recombination effects are characterized by electrochemical impedance spectroscopy measurements. As a result of improved light harvesting, dye loading, and reduced recombination losses, the hierarchical nanofibers yield 2.14% electrochemical conversion efficiency which is 50% higher than the efficiency obtained by plain nanofibers.     

Preparation of TiO(2) Nanocrystallite Powders Coated with 9 mol% ZnO for Cosmetic Applications in Sunscreens

The preparation of TiO(2) nanocrystallite powders coated with and without 9 mol% ZnO has been studied for cosmetic applications in sunscreens by a co-precipitation process using TiCl(4) and Zn(NO(3))(2)·6H(2)O as starting materials. XRD results show that the phases of anatase TiO(2) and rutile TiO(2) coexist for precursor powders without added ZnO (T-0Z) and calcined at 523 to 973 K for 2 h. When the T-0Z precursor powders are calcined at 1273 K for 2 h, only the rutile TiO(2) appears. In addition, when the TiO(2) precursor powders contain 9 mol% ZnO (T-9Z) are calcined at 873 to 973 K for 2 h, the crystallized samples are composed of the major phase of rutile TiO(2) and the minor phases of anatase TiO(2) and Zn(2)Ti(3)O(8). The analyses of UV/VIS/NIR spectra reveal that the absorption of the T-9Z precursor powders after being calcined has a red-shift effect in the UV range with increasing calcination temperature. Therefore, the TiO(2) nanocrystallite powders coated with 9 mol% ZnO can be used as the attenuate agent in the UV-A region for cosmetic applications in sunscreens.     

Formation and Morphology of Zn(2)Ti(3)O(8) Powders Using Hydrothermal Process without Dispersant Agent or Mineralizer

Synthesis of Zn(2)Ti(3)O(8) powders for attenuating UVA using TiCl(4), Zn(NO(3))(2)·6H(2)O and NH(4)OH as precursor materials by hydrothermal process has been investigated. The X-ray diffractometry (XRD) results show the phases of ZnO, anatase TiO(2) and Zn(2)Ti(3)O(8) coexisted when the zinc titanate powders were calcined at 600 °C for 1 h. When calcined at 900 °C for 1 h, the XRD results reveal the existence of ZnO, Zn(2)TiO(4), rutile TiO(2) and ZnTiO(3). Scanning electron microscope (SEM) observations show extensive large agglomeration in the samples. Transmission electron microscope (TEM) and electron diffraction (ED) examination results indicate that ZnTiO(3) crystallites formed with a size of about 5 nm on the matrix of plate-like ZnO when calcined at 700 °C for 1 h. The calcination samples have acceptable absorbance at a wavelength of 400 nm, indicating that the zinc titanate precursor powders calcined at 700 °C for 1 h can be used as an UVA-attenuating agent.     

高孔隙率 Ce-TiO2微粉的制备及其光催化性能研究

以自制Ce离子掺杂的TiO2纳米粉为前体,通过微波辅助水热法进行空间结构改性,获得改性Ce-TiO2微粉。所得样品用X射线衍射（XRD）、扫描电镜（SEM）、氮吸附（BET）、紫外-可见漫反射（UV-Vis）等测试方法表征。结果表明,所制备的微粉具有较高的孔隙率,平均孔径为153．4 nm,比表面积可达到154．9 m2／g。掺杂Ce离子对微粉的结构没有影响,但是拓宽了TiO2的可见光吸收范围,使吸收边红移至可见光区域,同时有效的抑制了晶粒长大,阻碍锐钛矿相向金红石相的转变。所制备的高孔隙率Ce-TiO2微粉在低浓度甲醛溶液中表现出良好的可见光催化性能。     

两种合成方式对制备纳米二氧化钛粉体的影响

以钛酸四丁酯为原料,分别通过溶胶-凝胶法和硬脂酸凝胶法制得TiO2前驱体,在450℃煅烧后分别得到粒径在42.4,9.4 nm的混晶纳米TiO2。运用XRD和TEM等方法对TiO2进行表征,探讨了两种合成方式对纳米TiO2粒径大小及TiO2晶型转变温度的影响。结果表明,以硬脂酸凝胶法合成的纳米TiO2纯度高、粒径小,且晶型转变温度低,这是由于晶粒细化后晶型转变温度降低的缘故。     

电导法研究固—液界面的吸附：D354树脂吸附低浓度游离酸的行为

利用电导实验技术,跟踪观察３５４树脂吸附低浓度游离酸的行为,研究吸附体系的性质对吸附的影响。实验结果表明,Ｄ３５４树脂吸附低浓度游离的吸附速度大小顺序为ＨＣｌＯ４〉ＨＮＯ３〉ＨＣｌ。Ｄ３５４树脂的吸附活性中心是自由胺基。     

酸性溶剂对水热法合成 ZrW2 O8粉体形貌的影响

以水热法制备负热膨胀性ZrW2 O8粉体,考察酸性溶剂对粉体的合成及性质的影响。对其前驱体进行热重-差热分析,以X射线粉末衍射,扫描电子显微镜对产物结构及形貌进行表征。结果表明当加入的溶剂为HCl 和HNO3混合液时,能够获得结晶良好,纯度高的纳米ZrW2 O8粉体。但随着HNO3量的不断增加,颗粒尺寸逐渐减小,颗粒的形状从棒状转变为类球形。通过原位X射线衍射分析,表明所合成的粉体具有良好的负热膨胀性能。     

Morphology, crystal structure and adsorption performance of hydrothermally synthesized titania and titanate nanostructures

Titania (TiO2) and sodium titanate nanostructures with controllable phases and morphologies were synthesized by a hydrothermal method with titanium disulfide (TiS2) as the starting material. Sodium titanate nanobelts could be synthesized under a relatively low alkaline concentration (1 mol L(-1) NaOH) and short duration (6 h). At 3 mol L(-1) HCl, rutile TiO2 nanorods were synthesized. Anatase TiO2 nanoparticles were obtained at pH values ranging between 2 and 13. FTIR analysis confirmed the phase change as the pH of the reacting medium increased from highly acidic to highly alkaline. The adsorption of Methylene Blue (MB) on the as-synthesized sodium titanate nanobelts fitted well with the Langmuir monolayer model, with an adsorption capacity as high as 312.5 mg g(-1). The kinetics of MB adsorption was found to be a pseudo-second-order kinetic model. In brief, this study demonstrates a simple method to control the phase and morphology of titanium-based oxides. Excellent performance has been shown in the MB adsorption test by the sodium titanate nanostructures.     

金红石钛白煅烧晶种制备新工艺

介绍了金红石钛白粉生产中在NaOH/TiO2 比值为 2 1 ,中和终点 pH值为 3～3.5,消化酸度系数为 0 35～ 0 .5的条件下 ,高活性煅烧晶种的制备工艺研究情况 ,经实际生产运行验证 ,该工艺完全符合生产要求。     

金红石相纳米二氧化钛分散浆料制备及其复合电镀应用

以四氯化钛为原料低温水解 ,在液相中一步简单地制备了金红石相TiO2 ,并且原位制备了一定浓度的纳米TiO2 分散浆料。X射线衍射测试表明此TiO2 呈纯的金红石结构 ,透射电子显微镜观察发现此浆料分散性好 ,可直接在化学复合电镀中应用。采用常规的电镀过程在金属表面形成了TiO2 -Ni复合电镀层 ,比一般的镀镍层均匀、细致。     

Carbon-modified TiO2 for photocatalysis

ABSTRACT: Here we present a method to produce TiO2 nanocrystals coated by thin layer of graphitic carbon. The coating process was prepared via chemical vapor deposition (CVD) with acetylene used as a carbon feedstock with TiO2 used as a substrate. Different temperatures (400°C and 500°C) and times (10, 20, and 60 s) of reaction were explored. The prepared nanocomposites were investigated by means of transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy/diffuse reflectance spectroscopy and ultraviolet-vis (UV-vis)/diffuse reflectance spectroscopy. Furthermore, photocatalytic activity of the materials was investigated under visible and UV-vis light irradiation in the process of phenol decomposition. It was found that TiO2 modification with carbon resulted in a significant increase of photoactivity under visible irradiation and decrease under UV-vis light irradiation. Interestingly, a shorter CVD time and higher process temperature resulted in the preparation of the samples exhibiting higher activity in the photocatalytic process under visible light irradiation.     

TiO2体系对酸性红B的催化超声降解过程的影响

采用处理过的市售的锐钛型和金红石型纳米TiO2作为声催化剂,低功率的超声波作为激发源,研究了纳米TiO2对酸性红B催化超声降解过程的影响.结果表明:锐钛矿纳米TiO2和金红石型纳米TiO2对酸性红B有着不同的超声降解过程.锐钛型纳米TiO2以空穴氧化为主,使酸性红B脱色和降解过程同时进行,而金红石型纳米TiO2则以自由基氧化为主,是先脱色后降解.锐钛型纳米TiO2降解效果明显优于金红石型纳米TiO2.单纯超声照射下酸性红B没有明显的脱色和降解过程发生.因此,锐钛型纳米TiO2催化超声降解有机污染物的方法具有很好的应用前景.     

Synthesis of dandelion-like V2O3/C composite with bicontinuous 3D hierarchical structures as an anode for high performance lithium ion batteries

The dandelion-like V₂O₃/C composite was synthesized by a simple and facile template-free solvothermal method followed by a suitable thermal treatment. The dandelion-like V₂O₃/C composite is constructed by bicontinuous 3D hierarchical structures, which are formed by interconnected nanoparticles and interconnected pores, respectively. Moreover, the surface of interconnected nanoparticles is uniformly coated with an ultrathin carbon layer. Upon evaluation as an anode material for LIBs, the as-synthesized product shows superior electrochemical performance. Under the current density of 0.1?A?g^?1, the specific discharge capacity of V₂O₃/C composite is 737?mA?h?g^?1 after 100 cycles. Moreover, after 1000 cycles at a high current density of 2?A?g^?1, the sample exhibits a discharge capacity of 315?mA?h?g^?1 which is 94% of the first-cycle discharge capacity. This excellent electrochemical performance can be ascribed to its unique hierarchical structure with 3D interconnected nanopores and uniform carbon coating.     

酸洗提纯AlN粉体的研究

氮化铝(AlN)粉体中的金属杂质与氧化是影响其纯度和性能发挥的主要因素,而酸洗是提纯AlN粉体的有效手段.实验采用磷酸(H3 PO4)、硝酸(HNO3)、氢氟酸(HF)和盐酸(HCl)对AlN粉体进行酸洗提纯,主要研究了酸洗过程中酸液的选择与配比对提纯效果的影响.实验结果表明:这四种酸均显著降低了AlN粉体表面的金属杂质含量,而HF和HNO3的混合酸具有更好的提纯效果,特别能降低其中的Na、W、Fe等金属杂质,而且还可通过HF与Al2O3的反应有效去除氧杂质.HF/HNO3酸液的适宜配比为HF:HNO3=2:1,在该条件下酸洗后的AlN粉体中,金属杂质含量均下降到100 ppm以下,氧含量仅为1.2wt%.     

Effect of surface microstructure of TiO₂ film from micro-arc oxidation on its photocatalytic activity: a HRTEM study

Photocatalysis is a reaction that happens on the surface of catalysts around only several atomic layers. Therefore, the microstructure beneath the surface plays a key role for the improvement of photocatalytic property. In this paper, the microstructural variation of the TiO(2) film from micro-arc oxidation (MAO) was characterized by using a high resolution transmission electron microscopy (HRTEM), and the relationship between microstructures and photocatalytic activity was studied. The results revealed that: 1) The microstructural variation from the surface to the interior in the as-prepared film is as follows: an amorphous layer with thickness around 10-20 nm, an intermediate zone consisting of amorphous, anatase and few rutile TiO(2) phases with grain size about 12 nm, then the main structure consisting of anatase and few rutile TiO(2) phases with grain size around 20 nm. This variation was formed due to temperature gradient during MAO. 2) When the TiO(2) film was annealed at 450 °C for 12 h, the amorphous layer disappeared and crystallized into fine anatase grains, and, simultaneously, the grain size in the intermediate layer grew obviously from 12 nm into 18 nm, and the interior portion from 20 nm into 30 nm. 3) The photocatalysis experiments exhibited that photocatalytic activity of the post-annealed TiO(2) film was enhanced to more than twice that of the as-prepared TiO(2) film. Therefore, we propose that the crystallization of amorphous phase beneath the surface plays a key role for the improvement of its photocatalytic property.     

氮掺杂纳米TiO2的制备及其光催化降解酸性红B的研究

以钛酸丁酯和氨水为原料,无水乙醇为溶剂,硝酸为抑制剂,采用湿法水解制备氮掺杂TiO2纳米微粒,并用XRD、TEM对其进行了表征。在紫外光照射下,考察了氮掺杂催化剂光催化降解酸性红B的催化性能。以高压汞灯为光源对有机染料酸性红B进行了光催化降解实验,并研究了催化剂的类型、催化剂的用量、溶液初始浓度对酸性红B降解的影响。研究结果表明：氮掺杂纳米TiO2的光催化性能明显优于纯纳米TiO2的光催化性能。     

Asymmetric anatase TiO₂ nanocrystals with exposed high-index facets and their excellent lithium storage properties

In this work, we demonstrate a unique organic solvent system to synthesize asymmetric anatase TiO(2) nanocrystals with a bipyramidal structure, where the upper pyramid is bound by (201) facets, and the lower pyramid is bound by (401) surfaces. Due to the high surface energy of these (401) high-index facets, the nanocrystals tend to assemble on these facets to minimize the free energy, leading to the formation of a dandelion-like hierarchical structure.     

处理温度对锐钛型TiO2光催化活性的影响

高温处理锐钛型TiO2可使其转晶改变晶型比例,因此加热温度和加热时间是影响TiO2光催化活性的主要因素。通过该方法得到了可利用可见光的TiO2催化剂,并进行了可见光降解有机染料乙基紫的研究。结果表明,在TiO2和可见光共同作用下,乙基紫的光降解效果明显优于单独使用锐钛型、金红石型和按照转晶的比率混合的锐钛型和金红石型TiO2。