Electrodeposition of mesoporous V2O5 with enhanced lithium-ion intercalation property

Mesoporous vanadium oxide (V₂O₅) thin films were deposited electrochemically onto indium tin oxide-coated glass substrates from an aqueous solution of vanadyl sulfate using CTAB (hexadecyltrimethylammonium bromide) as a templating agent. For comparison, a control sample was electrodeposited without CTAB templating. Transmission electron microscopy and small angle X-ray diffraction indicated the presence of mesoporosity with a well-ordered lamellar phase in the electrodeposited films. The crystallinity of the V₂O₅ thin films was confirmed by X-ray diffraction. Cyclicvoltammetry and chronoamperometry were used to measure electrochemical properties of synthesized films. The mesoporous films prepared with CTAB templating had a much higher capacity and lithium-ion diffusion rate than the non-porous electrode prepared without CTAB templating.     

电位对α-Fe2O3和掺钛α-Fe2O3光氧化水电荷转移速率常数的影响

外加一定的阳极电位可提高未掺杂的α-Fe₂O₃和Ti掺杂的α-Fe₂O₃(Ti-Fe₂O₃)电极的光电流或光电化学氧化水的速率, 但文献中通常假定电位全部降落在半导体固体一侧(带边钉扎), 其对界面电荷转移速率常数的影响鲜见报道. 本文应用电化学阻抗谱研究了外加电位对这两种电极光电化学氧化水时界面电荷转移速率常数的影响.结果表明: 随着外加阳极电位增大,两种电极的界面电荷转移速率常数均增大,但速率常数增幅比理论预期的要小, 表明电位并不是全部降落在电极的亥姆霍兹层, 而是同时降落在空间电荷层和亥姆霍兹层(费米能级钉扎). 表面态电容测量结果表明光生电荷可在表面态中积累, 导致了电位在电极界面重新分布并提高了界面电荷转移速率常数.相同电位下, 光强越强, 光生空穴在表面态积累越多, 降落在亥姆霍兹层中的电位增加,电荷转移速率常数也更大. 与α-Fe₂O₃相比,外加阳极电位对Ti-Fe₂O₃的界面转移速率常数提高更为明显.     

Ni控制掺杂TiO2薄膜的光电化学及光催化活性

采用溶胶-凝胶法通过分步控制工艺制备了镍离子不同掺杂方式的TiO₂薄膜。通过甲基橙的光催化降解动力学来表征其光催化活性。结果表明：镍离子非均匀掺杂在掺杂量0.5%时可以明显增强TiO₂的光催化活性，而均匀掺杂提高TiO₂的光催化活性较小。光电化学表征结果显示：镍离子非均匀掺杂TiO₂薄膜的瞬时光电流信号较强，说明其光生载流子易于生成且分离效果较好；循环伏安曲线表明，光照时Ni非均匀掺杂的TiO₂薄膜改变了体系的氧化还原电位，说明了薄膜内建电场的建立。基于半导体的P-N结原理探讨了镍离子非均匀掺杂TiO₂薄膜的光催化活性机理。     

Metal-organic deposition of YBa2Cu3Ox and Bi2Sr2Ca1Cu2Ox films on various substrates starting from different fluorine-free metallorganic compounds

YBa₂Cu₃O_x (Y-123) and Bi₂Sr₂Ca₁Cu₂O_x (Bi-2212) films on various substrates have been prepared by Metal-Organic Deposition starting from different metallorganic fluorine-free compounds and using a very simple instrumentation. The processing conditions include a rapid pyrolysis step in air and an annealing step in oxygen for Y-123 and in air for Bi-2212. The films obtained have been characterized by X-ray diffraction (XRD) and the formation of a superconducting phase of Y-123 or Bi-2212 was confirmed measuring the critical temperature (T _c) with Ac-susceptibility and resistive measurements. Microstructure and final cationic ratios have been studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

Surface modification of thermoplastics by atomic layer deposition of Al2O3 and TiO2 thin films

Al₂O₃ and TiO₂ thin films were deposited by atomic layer deposition at 80-250 °C on various polymeric substrates such as polymethylmethacrylate (PMMA), polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE) and ethylenetetrafluoroethylene (ETFE). The films were studied with FESEM, EDX, XRD, contact angle measurements and adhesion tests. The film growth rates on the thermoplastics were close to the corresponding growth rates on Si substrates. The adhesion of the films was good on PEEK and poor on PTFE. All coated surfaces showed lower water contact angles than the uncoated thermoplastics. Furthermore, the water contact angles on all TiO₂-coated surfaces decreased upon UV illumination, most efficiently with crystalline TiO₂ coatings.     

Topotaxial formation of titanium-rich barium titanates during solid state reactions on (110) TiO2 (rutile) and (001) BaTiO3 single crystals

The orientation relationships of Ti-rich barium titanate phases formed by solid state reactions at high temperatures were studied using (110) TiO₂ (rutile) and (001) BaTiO₃ single-crystal substrates. Well-oriented Ba₆Ti₁₇O₄₀ islands were observed after a vapor–solid reaction of a BaO quantity equivalent to a nominal BaO film thickness of 1 nm with the TiO₂ substrate, whereas a thin film consisting of well-oriented BaTiO₃ and Ba₆Ti₁₇O₄₀ grains was formed after vapor–solid reaction of a BaO quantity equivalent to a nominal BaO film thickness of 50 nm with the rutile substrate. A topotaxial orientation relationship between Ba₆Ti₁₇O₄₀ and TiO₂ was found. Topotaxy is facilitated by a certain similarity in the oxygen sublattices of TiO₂ and Ba₆Ti₁₇O₄₀. The mechanism of the reaction occurring between BaO vapor and the TiO₂ surface at high temperature is discussed. On the other hand, several well-oriented Ba₄Ti₁₃O₃₀, Ba₆Ti₁₇O₄₀ and Ba₂Ti₅O₁₂ phases were observed to be embedded in the mainly forming Ba₂TiSi₂O₈ phase after a solid–solid reaction of amorphous SiO₂ thin films with (001) BaTiO₃ substrates at temperatures above 1000 °C. They were formed by a topotaxial reaction involving the transformation of (111) planes of BaTiO₃ into (001) planes of the Ti-rich phases by removal of BaO and insertion of TiO₂. Cross-sections of the interfaces between the substrates and the various reaction products are studied by (high-resolution) transmission electron microscopy.     

原位水解沉积制备高效氮化钽微球太阳能分解水光阳极

利用一种新的原位水解沉积方法,以在高湿度空气中老化的甲醇中作为溶剂,通过乙醇钽水解而成前驱体微球颗粒沉积,制备出了高效的Ta₃N₅微球光电极,其1.6 V（vs RHE）电极电位下的光电流值达到了6.6 mA·cm^-2。相反地,在新鲜的甲醇溶液中没有钽前驱体微球颗粒沉积。这表明甲醇中水的含量对Ta₃N₅微球光电极的形成十分重要。另外,本制备方法也能方便地在其他透明导电衬底上制备出Ta₃N₅。     

原位水解沉积制备高效氮化钽微球太阳能分解水光阳极

利用一种新的原位水解沉积方法,以在高湿度空气中老化的甲醇中作为溶剂,通过乙醇钽水解而成前驱体微球颗粒沉积,制备出了高效的Ta₃N₅微球光电极,其1.6 V（vs RHE）电极电位下的光电流值达到了6.6 mA·cm^-2。相反地,在新鲜的甲醇溶液中没有钽前驱体微球颗粒沉积。这表明甲醇中水的含量对Ta₃N₅微球光电极的形成十分重要。另外,本制备方法也能方便地在其他透明导电衬底上制备出Ta₃N₅。     

Thermal and photochemical effects on the structure,morphology, thermal and optical properties of PVA/Ni0.04Zn0.96O and PVA/Fe0.03Zn0.97O nanocomposite films

Ni_0.04Zn_0.96O and Fe_0.03Zn_0.97O with average diameter of 23 and 19 nm, respectively, have been synthesized by a modified sol–gel method to be used in the preparation of (100 − x)/x poly(vinyl alcohol)/oxide nanocomposite films, with x = 0, 1, 3 and 5 (in wt.%). A 125 W-Hg vapor lamp with emission above 254 nmwas used to irradiate PVA/Ni_0.04Zn_0.96O and PVA/Fe_0.03Zn_0.97O films. The effect on their structural, thermal, morphological and optical properties was studied by TG, DSC, DRX, AFM, UV–vis and PL spectrophotometry. The Ni_0.04Zn_0.96O addition on PVA films decreases the thermal stability of the polymer in inert and in oxidative atmosphere. In contrast, the Fe_0.03Zn_0.97O presence in the PVA films seems to increase the thermal stability of the polymer. The characteristic peak of the crystalline phase of PVA and wurtzite phase of the zinc oxide were identified through X-ray diffraction in both films. The crystallinity of the PVA film increases with UV irradiation and with the presence of Ni_0.04Zn_0.96O and Fe_0.03Zn_0.97O. The roughness of the PVA film was not modified by the addition of the doped oxides; however, it increases after UV irradiation, more significantly in the films containing the oxides. The PVA film exhibits absorption around 280 nm characteristic of π–π^∗ transitions related to carbonyl groups from residuals acetate, while the 95/05 PVA/Ni_0.04Zn_0.96O and 95/05 PVA/Fe_0.03Zn_0.97O nanocomposite films show absorption at the visible region which is characteristics of the band gap reduction of the doped oxides. The photoluminescence of PVA was modified by the presence of the oxides in the film. These nanocomposite films are interesting due to their thermal, mechanical (flexible) properties and low cost of production. In addition they are also able to exhibit peculiar optical properties showing potential to be used in photonic devices, gas sensors and organic solar cell applications.     

Mn4+掺杂Co3O4纳米纤维的静电纺丝法制备及其电化学性能

通过静电纺丝法制备Mn⁴⁺掺杂的Co₃O₄复合纳米纤维,利用XRD、XPS、BET、SEM和电化学工作站等对材料的结构、成分、形貌和电化学性能进行表征与测试。研究发现,通过Mn⁴⁺掺杂,Co₃O₄复合纳米纤维的电化学性能得到明显改善。当n_Co∶n_Mn=20∶2时,相应的复合纤维具有较大比表面积68 m²·g^-1,而且该样品呈现出清晰的氧化还原峰,在1 A·g^-1的电流密度下,放电比电容量为585 F·g^-1,这比纯Co₃O₄纳米纤维的416 F·g^-1,有显著提高;循环500圈电容保持率达到82.6%,而纯Co₃O₄纳米纤维则是76.4%。     

Water-soluble poly(2-(3thienyloxy)ethanesulfonic acid)/V2O5 nanocomposites: synthesis and electrochromic properties

Water-soluble conducting poly(2-(3thienyloxy)ethanesulfonic acid) (PTOESA)/V₂O₅ nanocomposite, (PTOESA)_xV₂O₅, was prepared by simply mixing PTOESA with V₂O₅ wet gel at room temperature. XRD data showed that the interlayer spacings of (PTOESA)_xV₂O₅ films are 14.0±1.5 Å and increased as the polymer content increased. These values are consistent with the insertion of polythiophene chains into the V₂O₅ layer gallery. The formation of alternative layers of PTOESA and V₂O₅ was further supported by depth profile SIMS analyses. Cyclic voltammograms of (PTOESA)_xV₂O₅ film showed two pairs of redox peaks with colors varying from orange, yellowish green, green, to purple blue, depending on the stoichiometry of the nanocomposites. Moreover, a synergetic effect was observed on the electrochromic properties of these nanocomposites. It was found that the optical contrast (ΔOD) of the composites is better than those of PTOESA and V₂O₅ at the film thickness from 150 to 500 nm. The oxidation optical response time of (PTOESA)_xV₂O₅ is independent of the stoichiometry and falls in between those of PTOESA and V₂O₅. At higher polymer content (x>0.5), the reduction optical response time of (PTOESA)_xV₂O₅ is smaller than those of PTOESA and V₂O₅. Variable temperature conductivity data showed that the conductivity of (PTOESA)_xV₂O₅ films increased as temperature increased, characteristic of thermal activated behavior, which was dominated by the interparticle contact resistance. The room-temperature conductivity of water-soluble (PTOESA)_xV₂O₅ films was in between those of PTOESA and V₂O₅ xerogel and higher conductivity was found in the composite with lower polymer content. The anomalous conductivity of (PTOESA)_xV₂O₅ with high PTOESA content may be due to the reason that the higher the polymer content, the bigger the grain size of (PTOESA)_xV₂O₅ film as revealed with scanning electron microscopy and AFM micrographs.     

Mn4+掺杂Co3O4纳米纤维的静电纺丝法制备及其电化学性能

通过静电纺丝法制备Mn~(4+)掺杂的Co_3O_4复合纳米纤维,利用XRD、XPS、BET、SEM和电化学工作站等对材料的结构、成分、形貌和电化学性能进行表征与测试。研究发现,通过Mn~(4+)掺杂,Co_3O_4复合纳米纤维的电化学性能得到明显改善。当nCo∶nMn=20∶2时,相应的复合纤维具有较大比表面积68 m2·g-1,而且该样品呈现出清晰的氧化还原峰,在1 A·g-1的电流密度下,放电比电容量为585 F·g-1,这比纯Co_3O_4纳米纤维的416 F·g-1,有显著提高;循环500圈电容保持率达到82.6%,而纯Co_3O_4纳米纤维则是76.4%。     

Preparation and Characterization of SiO2-MxOy(M = V, Sn, Sb) Thin Films from Silicic Acid and Metal Chlorides

The preparation of SiO₂-M _x O _y (M = V, Sn, Sb) binary oxide thin films by sol-gel method was investigated. The reaction of silicic acid with metal chloride (M = Sn and Sb) or oxychloride (M = V) formed homogeneous solutions. The dip-coating of slide glass and silicon wafer followed by heat treatment gave oxide films having Si—O—M bond. The changes of FT-IR spectra as a function of heat treatment temperature and molar composition confirmed the Si—O—M bonds. The sheet resistance of films increased with an increase on heat treatment temperature and decrease in the content of metal oxide M _x O _y . X-ray diffraction peaks were observed for the SiO₂-V₂O₅ films with high V₂O₅ contents and heat-treated above 250°C, while the others were amorphous. Oxide films heat treated at 500°C had a thickness between 340–470 nm.     

Highly increased capacitance and thermal stability of anodic oxide films on oxygen-incorporated Zr-Ti alloy

Heat treatment of Zr-24 at% Ti alloy with barrier-type dielectric anodic oxide films was conducted at 473 K in air to examine the thermal stability of the dielectric oxide films for possible electrolytic capacitor application. The anodic oxide film was formed by anodizing of the alloy at 50 V for 30 min in 0.1 mol dm^?3 ammonium pentaborate electrolyte. The anodic oxide film of 125 nm thickness was crystalline, containing both monoclinic and tetragonal ZrO₂ phase. It was found that marked thickening of the oxide film with generation of cracks occurred during heat treatment at 473 K. Thus, the dielectric loss was largely increased along with the capacitance increase. In contrast, the anodic oxide film formed on the oxygen-incorporated alloy remained uniform, and no significant increase in dielectric loss was observed even after the heat treatment. The capacitance of the anodic film became as high as 4.8 mF m^?2, which was nearly twice that on Ta. The high capacitance was associated with the preferential formation of tetragonal ZrO₂ phase in the anodic oxide film on the oxygen-incorporated alloy. Findings indicated that the oxygen-incorporated Zr-Ti alloy is a promising novel material for capacitor application.     

TiO2纳米管阵列负载不同形貌Cu2O薄膜的制备及光电性能研究

本论文采用阳极氧化法在金属钛基底上制备高度有序的TiO2纳米管阵列薄膜,然后采用脉冲电流法在TiO2纳米管阵列上沉积Cu2O,从而制备出Cu2O-TiO2纳米管阵列异质结复合薄膜。借助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)等表征手段,详细探讨了Cu2O沉积过程中电解液的不同扰动方式(静止、磁力搅拌和超声搅拌)对复合薄膜物相和形貌的影响。实验结果表明电解液的扰动方式会影响Cu2O沉积过程中的离子扩散和微区化学环境,从而影响Cu2O的形貌。通过漫反射紫外-可见吸收光谱(UV-Vis)和光电流性能测试可知所制备的负载Cu2O型TiO2纳米管阵列薄膜具有显著的可见光响应效应。     

Patterning Effect of a Sol-Gel TiO2 Overlayer on the Photocatalytic Activity of a TiO2/SnO2 Bilayer-Type Photocatalyst

TiO₂ films with a thickness of 75 ± 5 nm (anatase) were formed on SnO₂-film (580 ± 80 nm) coated soda-lime glass substrates (SnO₂/SL-glass) by a sol-gel method. Although the photocatalytic activity for CH₃CHO oxidation (_ex > 300 nm) significantly exceeded that of a standard TiO₂/quartz sample, it decayed with illumination time (t) at t > 0.75 h. Stripes of anatase TiO₂ films of 40 nm in thickness and 1 mm in width were prepared on the SnO₂/SL-glass substrate in a 1-mm pitch by photolysis of an organically modified sol-gel film. The TiO₂ patterning further increased the photocatalytic activity by a factor of 4.1 as compared to the non-patterned sample, and it was also maintained at 0 < t < 2 h. The flat band potentials of the TiO₂ and SnO₂ films are determined to be –0.34 and +0.07 V (vs. SHE), respectively, at pH = 7 by the Mott-Schottky plots. On the basis of the results, the outstanding patterning effects could be rationalized in terms of the vectorial charge separation at the interface between TiO₂ and SnO₂.     

氢氟酸腐蚀对α-Fe2O3薄膜光解水电极光电化学性质的影响

使用溶胶-凝胶法制备了α-Fe₂O₃薄膜,研究了氢氟酸腐蚀薄膜表面对其光电化学性质的影响. 实验发现,薄膜表面的孔洞和间隙随着氢氟酸浸蚀时间的增长而发生变化. 氢氟酸浸蚀5 min,α-Fe₂O₃电极的光电流降低;随后随浸蚀时间增加而迅速增加;当浸蚀时间大于15 min时,其光电流再次下降,但对浸蚀过的样品再次退火可以使光电流大幅增加. 通过电化学交流阻抗谱、拉曼和X射线光电子能谱分析,提出了两个影响光电流的因素：氢氟酸表面浸蚀造成薄膜表面的多孔性和结晶度降低. 为此,通过示意图解释了结合浸蚀和退火后处理两个步骤来增强α-Fe₂O₃薄膜光解水电极光电活性的原理. 相对于初始的α-Fe₂O₃电极,浸蚀并且再退火处理后,其光电性质更加稳定.     

中空Ta_2O_5/TiO_2复合光催化剂的可控氧化制备及性能

以钛粉、钽粉为原料,炭黑作为反应性模板,通过熔盐法在炭黑表面原位生长了TaTiC_2纳米碳化物涂层,并以所得TaTiC_2/C复合物为碳化物前驱体,再经可控氧化制备出中空Ta_2O_5/TiO_2复合光催化剂。采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、紫外-可见(UV-Vis)漫反射(DRS)及N2物理吸附等手段对所制备的光催化剂进行形貌、显微结构及孔结构表征。以高压汞灯为紫外光源,以亚甲基蓝为目标降解物,通过光催化降解实验评价中空Ta_2O_5/TiO_2复合光催化剂的光催化活性。结果表明,熔盐法生长碳化物涂层厚度均匀(20~30 nm),碳化物主要以TaTiC_2晶相存在且具有纳米级的颗粒尺寸。中空Ta_2O_5/TiO_2复合光催化剂同时具有200 nm左右的中空大孔结构及壳层10 nm左右的介孔结构。中空大孔和介孔的存在提高了所制备催化剂对亚甲基蓝的吸附能力。此外,TiO_2与Ta2O5通过电子能带结构的耦合,有效提高了光生电子和空穴的分离效率,从而显著提高了光催化活性。nTi∶nTa=2.5∶1.5时,相应的中空Ta_2O_5/TiO_2复合光催化剂表现出最佳的光催化活性,对亚甲基蓝的紫外光催化降解率高达97%。     

Investigation on the growth of CaCu3Ti4O12 thin film and the origins of its dielectric relaxations

Using the radio frequency magnetron sputtering, CaCu₃Ti₄O₁₂ (CCTO) thin films were deposited on platinized silicon substrates. The influence of annealing temperature on structures and morphologies of the thin films was investigated. The high annealing temperature increased the crystallinity of the films. Temperature dependence of the dielectric constant revealed an amazing different characteristic of the dielectric relaxation at ∼10 MHz, whose characteristic frequency abnormally increased with the decrease of the measuring temperature unlike the relaxations due to extrinsic origins. Meanwhile, the dielectric constant at high frequencies was close to the value derived from the first principle calculation. All these gave the evidences to ascribe this relaxation to the intrinsic mechanism.